OK
Maybe getting somewhere, just following Ninos advice, disconnected J1 J2 and J5, found a new fuse for under playfield.
Started machine up and pretty much as I expected, no blown fuse this time.
Powered off, plugged J1 back in, picked this one as it is only controlling one coil.
Checked fuse still OK, powered machine back, up, fuse didn't blow but noticed humming noise and discovered lower right thumper is locked on.
powered off, disconnected J1 from solonoid d board, connected J2,
Powered up, noted several coils firing at once, then the fuse blew.
So I think it is pretty safe to say there is something amiss in the driver board, where to go from here though??