Quoted from GILV:
Check if the wire colors are the same colors on both coils, if so, search for a bad diode on one of the 2 coils.
That's what I would do first.
It ended up being a switch diode!
A few months ago I had installed a replacement switch and totally borked the diode attachment (put it on the wrong leads).
Today, I referenced how other switches looked around there and copied that.
All good now!