TRS-80 Model 4 help requested

I recently picked up a TRS-80 model 4, that seems to have problems with its floppy drives. The machine is a base Model 4 with 64KB of ram (I think - haven't yet taken the EMF shield off the mainboard), and no peripherals attached. When I powered it up the first time, with or without a disk in the (bottom) drive, it displayed "Cass?" on the screen, and then I could press enter to that and the "Memory size?" prompt, and get a basic prompt. I tried swapping the floppy drives, and that time I got a "Diskette?" prompt if there was no disk in the drive, and pressing any keys didn't cause anything to happen. If I put a disk in the drive, the machine never displays anything, and then after 10-20 seconds, the drive light goes out. I tried connecting only one drive at a time, with the same results. If I connected a 1.2MB floppy that I had laying around (a Teac FD-55GFR-149-U), it did the same thing as if the drives were swapped. Yes, I realize that the drive probaly wasn't going to work, I just wanted to see if it did anything. Also, the disk I used was supposed to be a TRS-DOS (bootable) disk, but it's possible that they've gone bad after so many years. Are the disks on the Model 4 recorded so that I can read them on a PC (IE 48/96tpi MFM, compatible with the NEC D765)? I'd like to know if I can make backup images and/or see if the disks work on another machine. Thanks. Pat -- Purdue Universtiy ITAP/RCS Information Technology at Purdue Research Computing and Storage http://www-rcd.cc.purdue.edu