Update:

Definately a mechanical problem. My first tests were without cars. After pulling some cars it suddenly stopped while the motor kept turning. I think some gears must be broken or worn off.

Officially my first bad ebay purchase .

Is there a solution for this?

Bert

Definitely a broken gear. It slips along for a while explaining the erratic running and then just spins without moving.
I just replaced one and I will order a spare as dad has another Kof.

This gear is right next to the motor and has a massive reduction. 6/42 or something like that. However the 6 tooth gear is very small and quite weak. (diagram is misleading on the small gear size)

I highly recommend NEVER to push down on the lok to get it to pull more. Do what real loks do and haul less or double up on power.

Part number is E322102 or 442-322102 from Walthers. From the exploded diagram of the 36820 it is item #37.
The exploded diagram of the Koff III 36340 does not have the gear detail but I got confirmation that it is the same.

Hi!
Red light on the spare parts list means it will come again - and since Köf II is in production again, it shouldn't take very long (but may take a few months).

Wait for the green light if you want to order it from Märklin or order from a dealer that takes backorders.

I will try to find the part in Europe first before ordering in the US. They say on the website it will take 4-6 weeks shipping + payment is difficult. I have some pending emails to some european dealers of which I hope they have it in stock.

Another path I'm considering is building an axle myself. This way I can use metal (brass) gears that wont break as fast. I have found a thread in the stummi forum about this from 3 years ago. The guy claims he has found the required gears here: http://www.respotec.de/ . (see also http://www.stummiforum.d...;t=64178&p=1173728). Too bad he doesnt mention whether he succeeded or what exact gears were required.

I find it very difficult to measure on the broken gear, so if anyone knows the gear dimensions or has a good measuring method, please let me know.

My measurements of the 2 gears on the axle are as follows:

small:
11 teeth
outside diameter 4mm
inside diameter 2.3mm
pitch circle ~3mm (?)
width 2 mm

-> module 0.3

big:
30 theeth
outside diameter 9.6mm
inside diameter 7.8mm
pitch circle ~8.5mm
width 2 mm

-> module 0.3
-> this one is a bit helixical, which I don't know how to measure

axle itself:
diameter 1.5mm

bert

Maybe a small update on this.

After a tip on the stummi forum that ETS (http://www.modelleisenbahn.com/) had the part in stock I decided to order it there on monday (24/3). The thing is, I got an automatic order confirmation through email after ordering, saying a detailed invoince would follow, but I haven't heard from them since. I also have to add that I sent them an email on friday (21/3) asking whether the part was really in stock, which never got answered.

Can anyone who has dealt with this shop confirm whether this is normal? For me it is a strange way to manage a webshop, if you do not follow up web orders properly.

I did not yet pay anything, so that is not the issue, but I'm anxious to repair my kof.

Bert

Just wanted to let you know: I HAVE FIXED MY KOF!!

After some searching I found a matching gear at http://www.lemo-solar.de/ for an OK price to replace the broken one. It costs just 1 euro and is now of steel instead of plastic. I am confident it will last longer now. To be sure I have ordered a few more spare ones.

The other gear on the same axle is also available from them so you can replace the original axle with an all metal version. The required components have the following order codes:

191MB8: 11 teeth gear, module 0.3, width 2.5mm -> this one has to be made a little bit thinner(~1.8mm) to fit.
191MB9: 1.5mm axle -> this one had to be cut to 12mm length
ZR0330: 30 teeth gear, module 0.3, width 2mm. This is exactly the same gear as the big plastic one on the main axle, but in brass.

I hope someone else can use this info, as waiting for more than 6 months to get the Marklin replacement is a little bit long.

Running is now as expected, very smooth, no hickups. The kof surprised me with is pulling power on level track, it can pull my Me109-plane train without issues. Also current pickup is very good, better than other 2-axle locos like E69, Glaskasten or ET 194.

On top of this:
1. I have replaced the original decoder with a regular lokpilot 4.0. They are exactly the same size as the original one and thus fit perfectly. Main reason was 128 speedsteps and the ability to control headlights/rearlights independantly.
2. I changed the ugly dark yellow front LEDs with warmwhite ones. This was VERY difficult, since the original LEDs are not in a SMD package as you would expect, but are bonded directly onto the light PCBs. Especially for the rear lights the change was difficult since I had to solder the white LEDs next to the original red ones, that had to keep working (because my replacement red 0603 LEDs were too high). If you ever looked at a bondwire you'll know what I mean. So changing the LEDs is possible, but I do not recommend it to do it like this. Especiqlly if you have a heart condition ;). In this case it might be better to obtain original light PCBs from marklin with warmwhite LEDs on them. The result I have now though is stunning, the LEDs are really bright, totally unlike the original lighting.

Bert

Edited by user 21 April 2014 09:44:17(UTC)  | Reason: copy paste errors

It seems this issue with Köf locomotives might be quite common as I've seen more references to it since this thread was opened.

I purchased off eBay a rather nice looking 29524 set with a Köf loco and two red silo cars.



Giving the loco a test run I found it exhibited the symptoms Harald mentions above - motor can be heard spinning but no movement from the loco. Initially I wondered if it was a case of the worm gear on the motor shaft not being seated into the driving gear as if the the driving gear is moved by hand the loco's wheels turn OK.



I see from various Stummis threads that the small gear at the other end of the axle the driving gear is connected to can split.

https://stummiforum.de/viewtopic.php?t=76230

See the pictures in the Stummi thread about how to disassemble the loco and also the picture of a broken gear with a split in it.

I was fortunate to come across a German seller on eBay who has a pack of two E322102 gears, so I have ordered those, and will replace the one in my loco with one of those, with one as a spare.

Given the gears are plastic it seems that it is inevitable that they will wear out, so maybe getting metal ones as Bert has done might be a more permanent option.

I'm pleased to say that replacing the main driving gear / axle on my Kof with an original Marklin part E322102 repaired the loco.

It now pulls 5 freight cars without any issues. The loco was very slow to start off with even at full speed, but gradually sped up and was running OK in both directions after about 6 laps of my test oval.

I think trying to turn the wheels by hand is a No No as you will end up either striping the gears or causing the small gear to either break or spin on its axle. I suspect whoever owned the set before me did this then flicked the set off to get rid of the problem.

I managed to find the replacement gears on ebay - in fact the seller sold me a pack of two so I have a spare one now.

I found it best not to over tighten the four screws holding the bottom plate in as that causes the gears to bind up and seize.

Thanks to all above in this thread for their advice in fixing the loco.