Thanks much. New switch got here today, so will dive in over the weekend.
Saturday:
Got the dash panel loose by removing three screws at bottom as suggested by Firefox. Switch turned when I got vise grips on front trim ring; looked inside and switch-dashboard contact area is glommed up with dried, hardened caulk or glue. Wires at back of switch also covered thickly with some dried rubbery caulk-type substance. May have to pull steering wheel to make more room to work.
No combination of available pullers could get a grip on the steering wheel; if that turns out to be necesssary, I may have to make some sort of puller plate. Owning machinery is sure a constant learning opportunity.
This brief job has turned into an all-day meeting and dinner on the ground.
Seems like the PO who previously replaced this switch and glued it in also used a really good threadlocker on the terminal screws; I'll have to find a way to dissolve that, or I'll strip out the screw heads.
The switch was apparently glued in because it does not have the little protrusion which locks into a slot on the dash to keep the whole assembly from rotating when the key is turned. Now I see that my new replacement switch doesn't have it either...
QUERY: Does anyone here know of a way to cure that problem? E.g., drilling through the dash panel and into the switch body and inserting a pin or small screw?
[BTW, the bolts which hold the dash panel to the chassis are 8 x 1.25 mm tap bolts, 20 mm thread length. They appear to be used in a number of places on the tractor body panels.]
Sure glad I'm not billing myself by the hour.