Hello everyone. I've been browsing the forum for a while, great stuff from everyone. I've been collecting Marklin since I first got it for Christmas in the 80s. I've been unpacking stuff which has been stored for a while as I am setting up a new layout.

I have a 7051 crane that was purchased probably in 1989 or so. It has been in storage for about 10 years or so, I just got it back out. When I wired it all up, the motors are having trouble. The magnet works, but when I try and turn it left/right or wind the string up/down, it makes a dull buzzing noise. Almost as if the motor is stuck. I have lubricated it, but not sure where to go next? Maye replace the brushes?

Thanks in advance!

The axle shaft that goes up to the crane cab gearbox is actually a 2 piece item - there is a smaller shaft inside the larger outer shaft, and both of them need to turn freely. If the inner shaft has seized, you will need to take the shaft out of the crane and soak it in a bath of WD40 or CRC or suchlike to try and free it up.

Make sure that the other gearpoints have a drop of oil on them and can turn freely. Also, fit new brushes to the motors, as these may wear or seize, thus preventing the motors from turning.

I'm sorry not responding more quickly. I have the 7051 apart. The problem was, as suggested, that the screw shafts coming off the motors were seized into the green cast base of the crane. I actually had to let the oil sit a couple of days to get them free (oiling from the other oiling point). I am running it on a test transformer, and one motor is working great in both directions. The other motor works in one direction, but in the opposite directly, the light in the transformer dims and there hum, like a ground fault. I have a M* engine repair manual from the 80s and will see if I can figure it out based on this, but if anyone has suggestions I also appreciate. I don't see any obvious damage to the solder connections, although when removing the cover of the motor to get the drive shaft/copper coils out the whole thing seems very delicate. Any thoughts?

I will also try to come back tonight and post a couple of pictures of the point where the seize was to hopefully help in the future.

Thanks again!

In case you don't have the parts list. Does it appear that any of the shafts or gears are out of true or rounded?

Here are the images of where the shaft was seized. I wanted to share for anyone else having a problem. You can see the hole on green base where the drive shaft (attached to the armature) would go in has a white crust around it, probably dried up lube from years ago. It of course is now clean and moving freely.




Regarding the reversing, I will have to look into it. I actually just got one on Ebay last week as I suspected I may have damaged one of the armatures trying to get it un-seized. I will try and swap the armature from the 100% working motor to the motor that moves only in one direction to see if that helps. I also am running it as a test with the gearing removed, so there is nothing to cause any resistance against the motor. I'll report back once I get a chance to do this test.

The parts list is great! Thanks!

Thanks for the update. Nice to see that you have it working now.



r/Thomas