I've tried using SpinRite 4.0 with a few problematic MFM and RLL drives without luck and am wondering whether anyone knows of compatibility issues with some controllers. The ones I've tried are the WD1006V-MM2 (MFM) and WD1003V-SR2 (RLL) and with both I've configured the disk parameters in the BIOS. Oddly, SpeedStor works fine and can see the drives and find bad sectors but SpinRite doesn't show any disk information and claims there are no hard drives. I could dig out an XT board and try an older 8-bit ISA MFM/RLL card with an onboard BIOS but that would be a pain versus using the 286 system I have out.