Pressure Regulating Valve - How to Test??

Never, never, ever buy a new valve. They are junk...I mean JUNK!!!!

Did I mention they are junk?
OK ....junk they are. Here is my problem.

The front cavity of my M/C has very little fluid due to me opening the bleeder valve on the L/R. I attached a multi-meter and thought i would see "zero ohms" or a short due to the center piston in the safety switch moving and causing a short to ground. Unfortunately nothing, Do I have a bad safety sw? Fluid level in the M/C is just above the two open ports. Safety sw is original. In Line has them for $79.00. Might get one.