was building my TA-02 today and...

[edeneen 23]

no matter how much I messed and played with it, one of the spur gears seems to have a bad spot on it, it does not mess smoothly and seems to have a lump or flat spot

[kanerdog1x1 36]

Perhaps your pinion set screw is too long and is catching either on the spur or the gear case?

[Tamiyabigstuff 832]

Remove the motor & turn the gears to see if the problem is still there - if the problem has gone then check the position of the pinion on the motor shaft.

May be a case of taking it all apart and carefully rebuilding while examining each part for defects, following the assembly diagrams carefully.

These gearboxes normally go together without any problem.  

[svenb 3778]

could be a bit of muck/stone stuck between one of the teeth, had that on a tl01 once.

sven