FD400 drive troubleshooting

All: As you all know from previous posts, I?m having trouble with the drive system on my IMSAI. While I wait to receive a memory board and some other stuff from a friend of mine, Herb Johnson gave me some new energy in looking at the existing iCOM Frugal Floppy system. This system uses Pertec FD400 drives. One works perfectly, the other one has consistent CRC errors as evidenced by the CRC light on the drive cabinet, and BDOS errors reported by CP/M. I ensured that the spindle is engaging the diskette hub, and I also cleaned the heads using a wet cleaning diskette. Is there any common failure mode on this model of drive that I should start tracking down? I looked over the maintenance procedures for the drive and many if the tests allude to a diagnostics program that can manually control the spindle and head stepping. None of the iCOM manuals I have provide diagnostics code for manually controlling the drives in this manner. Before I start coding, does anyone have diagnostics code I can use? I found some code in the SIGM archive (for the iCOM 3712 controller) but it doesn?t seem to work properly with this controller. Thanks. Rich -- Rich Cini Collector of Classic Computers Build Master and lead engineer, Altair32 Emulator http://www.altair32.com http://highgate.comm.sfu.ca/~rcini/classiccmp