The exact thing happened to me. The tach is mechanically driven and on mine there was a kink in the cable which caused the internal drive cable to snap. The dealer came out to my house and replaced asap. The tech mentioned that he hasn't seen one routed like it was before so maybe a new guy at the plant ran routed a couple wrong. The dealer said it was not an issue for me to continue using the tractor withoiut the tach working, so I got a couple of "free" hours on it.