Tach question

[Kameroo]

Was out on a friends '84 Sea Ray 210CC this morning. His first day of the season, and the tach appears to be reading about 30% with everything else running just like before (speed, planing are the same).

Since it's a tach issue, where would you suggest looking? I'm guessing these instruments don't last forever :huh:

 

[midway]

The tach use to feed off of the alternator, so it could be an alternator output problem on the tach stud or the tach itself.

 

[Kameroo]

Looks like it came back to life. Winter gremlins.