I have a 1997 Bravo I that has worked flawlessly for many seasons. Years ago, I had upgraded to IMCO gears installed inside because of a Whipplecharger upgrade. Additionally, I have IMCO full hydraulic steering (single ram). Anyway....this season, my trim gauge suddenly began to malfunction. I would put my drive all the way down and the gauge would read it was halfway down. And, it just kept getting worse and worse....until now, with my drive all the way down, the trim gauge reads that it's almost all the way up. And, when I actually put the drive up, the gauge does move with it, but it's so "off" that it reads WAY higher than the drive actually is. The good news is that the drive is trimming properly, and the gauge is actually moving when I trim the drive. The bad news is....the gauge has somehow gotten way off and is no longer calibrated with the true trim heights of my drive. Does this sound like a simple gauge issue? Or, maybe the gauge is fine and it just needs to be recalibrated somehow? I feel like this must be a common thing, and surely someone here has knowledge of how to handle this. Thanks in advance for your help!

Trim sender is probably bad Part #6 https://www.mercruiserparts.com/8053...-kt-alph-brv-1

Since you mentioned one of the symptoms was partial movement, you may have a hinge pin bolt that
has come loose, remove the sender and see if the bolt is loose, it’s a 12 point Allen head