Kit drive train question

[zc923]

Before I go on, I should mention that I was apart of the building of the gearboxes for 1403.

While building the gearboxes, we had our fair share of trouble, but lets not go into that.

Currently, our problem is that when one of the gearboxes is active, it makes a clicking noise, which gets louder and louder in respect to the speed. The frequency of the noise is one per revolution. Its more of metallic click noise, but that doesn't describe completely.

When ran a series of trouble shooting things, and we have ruled out the sprocket, the motors, and the ball bearings. Upon closer examination, I noticed that the one of the setscrews had been grind-ed down, leaving it shiny. Yes, I did use the new setscrews, and they were shortened to sit flush. When I saw this, I looked at the gear that runs closest to the setscrews, and sure enough, it had chipped a few teeth.

But here is the strange part, once we remove that particular gear (this is the gear that is connected to the camshaft), the noise becomes louder.

Another curve ball, if only one motor is geared to it, the gearbox makes the noise of a beat-box.

I am positive that is was built correctly, because the other one works just fine.

Help is greatly appreciated.

P.S., is the setscrew strong enough to break/chip the teeth of a gear?