The tach in our '66 M20E started moving wildly 30 minutes in to an hour long flight, then made really loud buzzing/whining sounds, then it went dead. I pulled the sheath from the engine and the cable had broken about two inches from the end. Then I pulled the tach, inserted the cable into the tach, and it wouldn't turn. Frozen! Do you have a suggestion on what we should use as a replacement (with a light)? Thanks.