I verified last night that the amp will not play with the impedance switch on 2ohm. I swapped the speaker cables around, connected the cabs together (series-like) and then ran both from the head (parallel-like) and got nothing with 2ohm selected.
I then rehearsed with the band blasting through the 4ohm 610 Ampeg cab and it sounded perfect, great, full and loud.
B, I flipped the rocker a bunch and even powered the head down (still clinging to false hope) and powered it up in 2ohm... and still heard nothing.
When I had the head at home, I popped the top and bottom off, cleaned about ten years of muck off the fan and gave it a good inside dusting. I was tempted to pull the motherboard out to get a better look at the switch... but chose not to.
Consensus still bad switch?
Sadowsky Fender Ampeg Eden SWR