OOB switch replacement.
OK – I’ll answer my own post.
The OOB switch completely failed. Access to replace it is quite simple, remove top panel, undo screw for panel underneath, slide out to the right then up, and you can access the switch.
I repaired it today (Saturday), F&P Parts closed, but it’s a standard spst normally closed (NC) microswitch you can get from any electrical parts store for a few dollars. (or use one with NO and NC terminals, and chop off the unneeded terminal with sidecutters.
Take care when replacing lower panel, wires and (water level sensor?) hose need to be pushed back in to slot on RH side, or the hose will be crushed when fitting top panel and cause other problems.