Problem with RF73 DSSI disk

I just acquired a KA640 VAX in a BA215 (thanks Josh) which has one working RF30 and one dead RF30 with failure code 300B(X). I don't have copies of any manuals which list the error codes. I just figure at this point that the drive is dead and there is nothing that can be done to try to fix it. The working 150MB RF30 is too small for a useful VMS system although it would be a decent size if I set up the system as a PDP-11 with an M7554-PB KDJ11-SB CPU instead of the VAX KA640. For VMS use I would either set up this system with a CMD Q-Bus SCSI controller, or use an HSD10 in a BA350 to connect SCSI disks to the DSSI controller. Starting DUP server... Copyright ? 1988 Digital Equipment Corporation DRVEXR V1.1 D 5-MAY-1989 13:18:42 DRVTST V1.1 D 5-MAY-1989 13:18:42 HISTRY V1.0 D 5-MAY-1989 13:18:42 ERASE V1.3 D 5-MAY-1989 13:18:42 PARAMS V1.2 D 5-MAY-1989 13:18:42 DIRECT V1.0 D 5-MAY-1989 13:18:42 End of directory Task Name? PARAMS Copyright ? 1988 Digital Equipment Corporation PARAMS> STATUS Configuration: Node R3Q0UA is an RF30 controller Software RFX V103 built on 5-MAY-1989 13:18:42 Electronics module name is ZG95105350 Unit is inoperative, error code 300B(X) Last known unit failure code 300B(X) In 100000 power-on hours, power has cycled 216 times System time is 5-MAY-1989 13:21:44