Hi
Z-gauge is very sensitive to dust and often has pick-up issues. This discouraged Märklin to produce a digital version which they once considered.
Pick-up issues involve:
- rail cleaning
- wheel cleaning
- contact tongue cleaning
- design issues: the contact wheels should be suspended so that all contact the rails. Of course the number of axle picking up the current and the weight (pressure wheel-rail) are key factors. So larger models tend to be "less fussy"
- a layout that is fully protected from dust (glass cage) is a good option

Rail groves, etc: Some say that cleaning rails and wheels should never involve an abrasive material (sand paper even of the finest grain (1500 or better) because it creates groves on the rail surface which allow dirt to stick to. Better have a very polished surface

Sorry for all those things you knew probably already
Cheers
Jean

Hello hope all is well.

There are some great suggestions from Jean and Chris. Many time’s erratic or inconsistent operation can be attributed to a need for cleaning. That Br 24 is a great little locomotive which is only held back because it must pull a coal tender. The motor and frame are essentially identical to the Br 74, tank locomotive a long time standard for the z scale starter sets.

I tried to think about something different you could check besides what was mentioned above. Here goes:

When your 24 reaches that spot where it stops, is the movement direction forward? Does it respond if the direction is reversed or must you push it? What happens if you run in reverse thru that spot? Is this problem a new occurrence or has this locomotive always had this issue?

Is the surface of the track undamaged? Is it ballasted track? If it is ballasted, where is the nearest fastening nail? If the nail is pressed in to far, it causes deformation of the two rails and this might not be noticeable unless examined closely. This might be enough to stop a 24 where a 89 will move right thru. The 89 is also a great long time starter set item, because it is simple, relatively heavy and with the short distance between the first wheel set and last wheel set it has exceptional contact with the rails. Comparing the two, the 89 might have an advantage for smooth operation but has a disadvantage because of its small size.

I suggest examining the locomotive to make certain it is ok and not damaged. Is the bottom cover fastened tightly. I had an early 89 which I had never had apart. It would work fine most of the time, but became noisy and a bit inconsistent. I looked it over and discovered one of the copper wheel contacts had twisted out from behind the wheel. Running on the top of the wheel instead of behind, allowed it to operate but not as it should. Perhaps something like this has happened to your locomotive. Fixing this might be a challenge as Chris mentioned. Also, once bent, this part never operates quite right and Marklin might not have a new part available. You would need to find it in the secondary market which is not necessarily impossible.

Hope this helps. A 24 and 89 are excellent locomotives and should not cause you problems. I also like the v100/212 locomotives too. Definitely a favorite of many. You would not be disappointed with this locomotive.

Take good care.

Dwight