I was running a P2K2 Pro all last year, with the same gearing... 18T pinion... believe me I have had my unintelligent experiences with bad gearing, haha. I guess you just gotta learn the hard way (by burning out a few motors and not understanding why and getting very frustrated and yelling)!
No comm drops were used... but I'll keep your suggestions in mind.
One thing I do not under stand is exactly what is a brush shunt? Is it the wire coming off the brush or the little crevice that the brush goes into to connect with the commutator? This is one thing I was always wondering upon..
But.. I'll keep all your suggestions in mind as far as spring tensions and what not, thanks