Last year I picked up a 2001 13 Whaler with a 40 Merc 2 Stroke from a fellow 2cooler and the tach worked fine. The last few times I have run it the tach hasn't worked. The motor is running fine and the lights come on the tach, but it either doesn't read the RPMs at all or they aren't close to accurate. Could is just be the connector(s) to the back of it aren't making good contact or corrosion due to moisture? Something else along those lines? I'm hoping it's a simple fix I can do myself and am looking for some guidance. Thanks for any help.