Thanks for the replies, with the end of school and a upcoming vacation I didn't get a chance to take apart the tank till today.

The issue was in the gearbox, on one of the reduction gears the inner set had become almost completely stripped off causing that side to operate very intermittently and becoming progressively worse as it lost more teeth.

I e-mailed Walterson's inquiring about replacement parts, but from what I've seen VSTank only sold the gearbox and motors as a whole, which is fine, but if I could just get extra gears I'd prefer that.

I was thinking of taking a chance on a pack of DIY toy/gearbox building gears, some of them appear to be pretty similar to the broken gear.