JD 4600 Yanmar 4TNE84 engine rebuild problem - Crankshaft balancer

[desmetde]

Probably a safety switch.

Do you still have your seat presence safety? That one kills the engine. The others keep you from starting, IIRC.

As for the interesting problem with the balance shafts, I suspect not only the crankshaft does not swap with the non-shaft version, possibly the pistons don't either. I have rebuilt 4 of the 3-cyl versions of this engine (3TNE84), and the pistons have steel weights cast into their undersides. No balance shafts.

I found the problem in the seat safety switch, thank you for all of your help!!
Dan