Used Tech Info Kill Switch and Tach Jumps
 

I followed the instructions and the switch works beautifully. The tach also works but now jumps intermittently - never a problem before. The engine has no cutout or other effects relating to the jumping tach. Loose ground the cuprit? Bad switch (a $2.50 item from local autoparts store).

I have a similar setup on the 911 with no issues.

I will play with the wires tonight and make sure all the connections are snug. I do not own an ampmeter (I have destroyed two)

Update - all wires and connections are sound, BUT when jamming the rocker switch into my secret location, one of the male spades wiggles just a bit. Will replace the switch tonight and jam it back with less enthusiasm. Film at 11:00.