just another odd peterism

So here is what happened. I went to the S10 with the intention of installing a new tach (measures how high the engine is revving) the truck has a factory tach but it won’t work. My plan was to cut the dash where the old tach is, remove the tach and install the new tach in its place. This would have given the truck a very clean look as well as keeping the “hotrod” theme so I went ahead and pulled the instrument panel and pulled the old tach out and had a look. I fit the new tach in its place and began to wire it. Here is where it gets annoying. I also pulled the dead volt meter and just for fun tested it. And the dadblasted thing works perfectly. Hmmm. So I pulled the old tach and hooked it directly to the engine. Then I started the engine and the tach worked. So do the other gages when I pull them out and when they are wired directly, they all work. So me being the smart person I am I figured there must be a simple wiring problem. Please oh please let it be a bad ground! It very often is and that is an easy fix, but no such luck. This is a power problem. No power is getting to the gage cluster, so I figure I will simply wire past the cluster and make the gages work individually. Here is the aggravating problem… I can’t bring myself to wire past everything (6 gages) when I know full well that there is very likely only I wire that is causing me issues. I WANT TO TAKE THE EASY WAY OUT! But I won’t and I will spend millions of hrs tracing down some stupid problem so that I can fix it to do exactly what it would do if I took the easy way out. Sigh. On a better note, the tach works!
P.S. this is my air compreser