airguide rpm gauge

[elmo robichaux jr]

I am restoring a1971 ranger with a 1976 85 HP Evinrude . it has a Airguide mod 1024 rpm gauge which was working fine. I changed the battery and it did not work any longer. I changed the rectifier and now it jumps all the way up to 6000 rpm at idle. I am trying to keep the boat as original as possible and need help with this problem. I am new to I boat forums and would appreciate any help anyone can give me THANKS

 

[sam am I]

The RPM gauge was working fine and for example, the day before you simply changed out the battery and the next day POOF, it wasn't working, dead to the world? Curious what then made you change out the rectifier? Was the battery not charging as well? Battery wires weren't reversed or anything crazy happen when the new battery went back in? No re-wiring?