My tach recently decided to stop working on my 1998 Z28.... most of the time.. It appears to be fairly random whether it decides to work or not but more often than not, it doesn't. If I start the car and it does work then it will continue to work until I turn off the car then it's random chance again. But sometimes if it doesnt work when start the car it may come on later.

I believe there must be a loose connection somewhere that it only works sometimes. But I don't know where to look. Is the tach mechanical or electronic? Should I just take it to a shop or a dealership?