I have the TireTraker system. The monitor and the sensors look exactly like your unit. I, too, think that you are over tightening the caps on the sensors. Just finger tight and nothing more. With that being said, I do not like my system. Too many ...
Can't speak for the 211z, but I believe my 211k advises to only use an external HD as a DVR which has an external power connection. No passing the power via USB. I am currently using a WD 750gb drive which I had sitting around for several years of p...