Jumpy tach - 3k to 4k range on B2500

[Ranger Dave (B25)]

Gents:

Noticed on a road trip today that my tach is getting silly. At speed (about 65-70) I should be turning just about 3k on the tach. Mine jumps around erratically between about 3-4k. If I thump the cluster lens, it settles back in where it should. At least for a while.

Anybody know what's going on with this? Tach's the only thing affected, no other gages are doing anything out of the ordinary.

Thanks in advance.

 

[johndeeregarner]

You may have a loose wire in the back of the cluster. I'd check all the connections on the back of the board.