MTH HO 4-8-4 problem

[scoobydo]

I have the 4-8-4 American Freedom Train (80-3119-1) from MTH and have been having some problems with it.
It has began to lose the chuffing sound and speed control functions.
It will begin to creep around the track accelerating and decelerating in a jerking motion. The speed will be the same even at full power, it is just a steady roll with the jerking.
All sounds will work including all the functions, just not the synchronized chuffing and speed. When I bring the throttle down to stop, it will continue going for several feet before stopping.
I have been able to get it out of this mode sometimes by changing my direction rapidly a few times. It seems to snap it out of this mode and then returns to normal, but it will come back again. Today I have not been able to get this to work.
Anybody ever have a similar problem?
Is it time to send it in?
Its out of warranty.
I'm running an MRC Black Box coming from an MRC basic power unit going to a small 4 foot oval.

Everything is clean, oiled and maintained properly.
I have several other trains that run flawlessly including Several other MTH steam trains and a few Athearn Genesis steam engines.
This one seems to be the only one with this problem, so I have ruled out my track setup.

 

[ianacole]

Have you done a reset on the unit?

 

[scoobydo]

Have you done a reset on the unit?

Definitely. That is the first thing I tried.
It seems to go into this mode kind of randomly.
Today, I took it off the track to take a look at it once again.
When I put it back, it went to working like normal.
About an hour later it started up again with the hiccups.

 

[ianacole]

It almost sounds like a connection is loose, or the decoder has worked itself loose (or some dust has worked its way into the connection).

 

[scoobydo]

I tried something that should not have worked, but it seems to be working fine currently.
I placed the train on the track with power, but did not turn it on. (F3)
I left it there for about an hour and then tried it and it seemed to work fine.
I know O guage trains have batteries, but I did not think the HO versions did.
I'm thinking what I did had nothing to do with the problem as it has run fine in the past and then the problem has returned.
It does almost seem like it is not getting enough power, but like I mentioned, my other trains are running fine.
Not sure what to do. If I send it in in its current state, I'm sure they will say nothing is wrong since it is running fine.
I think i will wait until it happens again and then record it so I can show the repair center.
Really strange.

 

[Motley]

Remove the shell and check for any loose connections. It sounds like a wire is loose on the decoder or something. If you see a loose connection I would try to solder it if you have the skills.