I'm having some odd problems with a 7906 drive. I have the service manuals, and it passes all the tests contained therein. However, none of those tests involve writing, and reads done offline with the DSU are not verified. The read/write testing relies on the diagnostics running on the cpu. I have the diagnostic software for the 7905/06 drives and it does find problems (sporadically). However, the dump it gives when it finds a problem is somewhat less than succinct - looks like you have to have the manual for the diagnostics to decode the dump, which according to the service manual can point you to a specific circuit in the drive electronics. Sooo does anyone possibly have the documentation/manual for the HP 7905/06 diagnostic program? Hoping for electronic format so I can look at it quickly. I'm itching to get to the bottom of this.