Looks like everyone has posted good tips for you and covered most of all the known problems with the gearboxes.I'll add a couple more things that might be helpfull.If you have allready got the tank open to check for problems and just overall conditions of the interior workings,which is most likely a good idea from the start.(have found loose screws in several of my tanks that were just somehow left inside them.
) One thing that can cause a gear box to run slower is a bent housing where the motor attaches to the side of the gear box.It is not uncommon to open up a tank and see the motor mounting area bent outwards (which means the pinion gear is to loose and not making good contact with the gear--not properly in line with the gear and will cause excessive ware on the gear) The oposite can also apply where the motor mounting area can be bent inward and puts excessive pressure onto the pinion gear and causing the motor to run slower than it should which can make the motor run hotter than normal and will cause pre-mature bearing failur in the motor.This may or may not be a factor in your case.??The final thing I'll add is it is not uncommon to find that some of these gearboxes will have little shim washers placed in the cross members that space the two halves of the casing,and also hold them in place.I have found some with shims that didn't need shims,and a lot of times you will find them that need to have shims added.This can apply also to the individual gear shafts,sometimes you can add a small washer that fits the shaft well to one side or other to line the gears up better and take out some of the sloop between the gear side and the bushing's.If this procedure is done carefully you can improve the over-all running and alignment of the gears in the gearbox. Hope this makes sense---
As we all know these are inexpensive tanks and a lot of the assembly line work leaves a lot to be desired.But for what they cost over-all we can be glad they are there for us to buy and injoy.
P.S. The quality control expert is the guy going into the building in the morning to go to work with the dark glasses and a white kane.
BIGMIG
