In a way I'm lucky then. The crystal is on very
long legs, hovering above
the board, and it was completely obvious that it wasn't attached as it
should be. Easier than an invisible fault.
That doesn't sound original to me. Every Apple ][ I've seen, and every
picture I've seen, has the crystal mounted close ot the board.
Had this been a Europlus, I would assme it had been converted from a US
version at some point (the mod, as I am sure you know, involves vuting
and sumpering some sodler pads and chaning the master clock crystal). I
assume you've checked the crystal is the right one, and that the jumper
pads are in the right states.
-tony