MDT Plymouth - worth repairing?

[drabina]

I have had the MDT Plymouth switcher for a while. Going forward, the gears will lock up once every revolution. Reverse works fine. From time to time, this prevents the engine from starting. Once it is running, it works fine though it will sometimes stall at low speed. I was never able to find the problem as none of the gears have broken teeth or any problems that are obviously visible. According to Bachmann's website, I can send it out for repair or replacement with the check for $15. Add $5 for shipping and I am out $20 for a switcher that usually sells for $25 (or less on Ebay). Is it worth saving this little switcher by sending it out for repair? Obviously it is not my only engine so it is rarely being used anyway.

[Joe323]

I guess it depends how emotionally attached you are to it.  If it does not have to be the exact same switcher I would just buy a new one

[richg]

Have you pulled the wheels and checked the gears up close? Not difficult to do. I have pulled mine part to isolate the motor contacts and convert it to DCC.

Rich

[drabina]

I am not attached to the engine at all. I just need to decide if I should fix it or toss it. Running this switcher in its current condition is very frustrating.

I have removed the body, cleaned wheels, inspected the gears but I can't find anything wrong with the loco. Most likely because I have no experience with model train engine troubleshooting.

[jbrock27]

Out of curiosity drabina, do you think the problem comes from running it in forward a lot more than running it in reverse?  Which is why it runs ok in reverse but not forward at this point in time.  The only reason I bring it up is perhaps that can help you chase down the problem, ie: a wear problem.  Of course, I don't know if this makes it any more repairable, but maybe points you in the right direction (no pun intended )

[drabina]

Out of curiosity drabina, do you think the problem comes from running it in forward a lot more than running it in reverse?  Which is why it runs ok in reverse but not forward at this point in time.

The problem occurs only in the forward motion of the gears. Reverse works fine. Basically, when I spin the motor manually, once every gear revolution, something catches and gears stop. Applying a bit stronger force gets the gears moving again so when the engine is running, the problem is not really visible. Only when the engine is parked and gears are close to the stuck point, I can't get the loco to start. Also when the engine is moving slowly it sometimes stalls because of that.

[jbrock27]

Yes, I understood from your original how it runs fine in reverse, but not in forward.  What I am asking (or should have been clear in asking) is, have you primarily run this loco in forward for most of it's life?

[drabina]

Yes, I understood from your original how it runs fine in reverse, but not in forward.  What I am asking (or should have been clear in asking) is, have you primarily run this loco in forward for most of it's life?

I am not an original owner of this engine but since I got it, I have run it in both directions. I would say about 60/40% (forward/reverse).

[jbrock27]

Did it always have this trouble from the day you got it or did it show up later?
I take it, this is HO gauge?
Do you know if this is an 1980's era model?

[Ken G Price]

Drabina, Did you use magnification to look between the teeth of every gear? Sounds like a very small piece of debris stuck in there.
This has been the case when I have had an engine act up this way. You may have to remove all of the gears to see between the gear teeth, but it may be the only way to look at them.

Then when you are done doing this, the junk box will still be there if needed.

[jbrock27]

I agree with KennyG, but where I was going with this was to try to establish if this is model that is prone to axle  gear cracking, first.

[Len]

I've seen this with a couple of other single end drive locos. It's usually one of two things. With the shell off, watch the motor shaft and worm gear closely when you apply power:

In forward, does the motor shaft and gear move out, away from the motor body as power is applied? If so, use a pencil to keep it from shifting and see if you still get a jam when power is applied. If not, you need to either press the worm farther on to the shaft an amount equal half of the shaft movement. Or install a shim to prevent the shaft from moving out from the motor.

If the motor shaft isn't moving relative to the motor body, is the entire motor loose? Being loose even a little can allow the drive shaft to get cocked at an angle relative to the worm wheel, creating a jam. This usually happens in only one direction, as the motion in the opposite directly tends to pull the worm tighter into the worm wheel.

Len

[richg]

I just realized I have the Plymouth with the pancake motor. Yours must be the newer version with a can type motor.
I have seen your issue when the worm on the motor shaft moves too far when connected to the work gear or the worm is not properly positioned.

Rich

[richg]

Another issue comes to mind. The worm will push the worm gear to one side in one direction. The opposite direction in reverse. In the bad direction, the worm gear might be hitting part of the frame depending on the installation. Worm gears are cut at an angle to match the worm.
Not so with the remaining gears which are spur gears. Those pretty much run straight with little side to side motion.

Rich

[Doneldon]

drabina-

You've answered your own question. Let me paraphrase: "I have a used locomotive with I don't know how much time in
service. It doesn't operate reliably and it will cost me about $20 to fix my somewhat mysterious problem. There is no
guaranty that there isn't another problem which hasn't shown itself due to the identified problem and there is no guaranty
that another problem won't soon develop in this older locomotive. Or ... I can throw another $5 at the situation and get a
new locomotive from eBay faster than I am likely to have my wounded unit returned from Bachmann. Plus, if I purchase a
new loco I can use my old one for parts, experimentation or as part of a diarama on my layout." Now make your decision.

                                                                                                                                      -- D