Half speed forward, full speed backwards

[Patriots fan]

Ok. Just broke out my HO set from when I was a kid. Bought a new locomotive for my boy and tried it out. Went great then it derailed on a switching track and now only goes half speed at the best in forward gear  Backward works great. The tracks are 30 years old. Did it short out the motor? 

[jbrock27]

PF, if you take the loco off the track and take a look at the trucks (wheels) at the end of the loco where the derail took place, can you see any difference between those wheels on the loco and the wheels at the other end of the loco?
Also, what make,  model loco are you asking about?

PS-sorry to hear you are a PATS fan

[GG1onFordsDTandI]

I had an N scale loco do that faster in reverse bit after a short derail, it was the motor. I think the newer power packs have features to help minimize the quick burn of small motors. Those old set power packs (all brands) weren't very good in the circuit breaker dept.. Looking for hairs, fuzz, etc. around axles, and gears would be my first move. Have you run the train going the opposite direction to see if the "slow" moves to reverse and forward speeds up? If the problem moves when the direction of the front of loco is changed, its your power pack, otherwise the engine motor is suspect. Do you have access to a multi-meter (ohm meter)? 

[AGSB]

There is some slop in the drive mechanisms on locos and possibly the gears are binding when going in one direction but are perfectly OK when going in the other direction. This could possibly be causing the problems. The only way to determine this is to remove the shell and observe the loco running in either direction.

[electrical whiz kid]

J. Brock; think you might have nailed it on the head.  BTW:  Did you watch the Pats V Bills yesterday?   Did you like that 83-yd run Blount did?...
Rich C.

[jbrock27]

Watch the PATS!?  No way, I watched the J   E   T   S,  JETS! JETS! JETS!.  And the tail end of the GIANTS game.