OK, take two. Blizzard 1260 is definitely dead. Does anyone still repair these? Otherwise I might get one of AmigaKit's 1230s to replace it. 1260s are far too expensive (and totally useless, these days) for me to want to buy another one of those. The SCSI module is on my other 1260 (tower version), so it's not that. I've tried removing the SIMM and it's not that either.
Opened everything up again and reseated the Indivision. This time I get the logo on bootup (aha!) and it works! I still get the occasional flicker, and I also get what looks like ghosting when I switch to the 1.25x setting, but *this* is the kind of output I was hoping for.
I've had to use a longer IDE cable and fit the hard disk sideways so that it overlaps the power socket and the PCMCIA port. How would I go about replacing it with a Compact Flash card?
Thanks guys for giving me the incentive to take it all apart again!