I have a set of V1 MadDad gauges. I replaced the oil pressure sender unit about 16 months ago. Recently, I have noticed that at idle when warm, the pressure on the gauge drops to 15-20 PSI, and then "dances around" between 15 and ~35. My oil level is fine, and I don't seem to be having problems when my RPM's are up. Is this a sender malfunction? Or possibly a bad ground? Any other ideas or ways to test what the problem is? Thanks a bunch!