I have had some issues with my 641 and the starter switch, often having to do the screwdriver to ground bypass. I have replaced the starter switch a couple of times already.
This time I was just getting a little spark when trying the screwdriver bypass. I put the battery on a charger and then she started up right away (no screwdriver needed). And she ran real good thereafter.
However I did notice a couple of odd things.
1. The charging light on the tractor was really bright and stayed on the whole time the tractor was running. Typically the light will have a mid-glow when turning the ignition and go off shortly after running.
2. The fuel gas gauge no longer works (the oil pressure gauge works). Happened at the same time as #1 as far as I noticed.
The tractor had not been started for a couple of months prior to this. I was wondering if my bypass technique caused something else to short out.