i saw an electronics repair technician today testing for bad electrolytic caps. he was using a huntron tracker 2000 curve tracer. i was kinda confused because he was putting one lead on the leg of the capacitor and the other lead on the metal casing on top of the cap. if it is an ellipse it is good, any other waveform means its bad. the thing i was confused about was why he was putting a lead on the casing of the cap? i just measured from casing to each leg with my ohm meter and im getting double digit Megaohms. this shows that the case is NOT in common with either leg. Please Explain!!TY!!