My Apollo 1240 sometimes doesn't find Fast mem either, but that generally goes away after a hard stare for 2 minutes
Try reseating the Mach chips. They tend to become a bit loose here.
I managed to use the scsi module for quite a while (even under OS3.5/3.9) but it takes some doing. Basically, you need to use the supplied floppy to put the drivers on the disk (the device must be on the disk, not just the filesystems). Otherwise it will just crash under anything newer than 3.1. But it shouldn't not find the disk...
