MicroVAX I (One) disk controller problem

Some weeks ago my MicroVAX I disk controller died together with the disk. I guess they got used to each other so much that they passed away collectively ... I used a Webster SRQD11-B/02 MFM controller and an ST-251 formatted as an RD52 (the SRQD-11 allows to mimic almost arbitrary disk types). I have no replacement SRQD11, but an RDQX2 and an RQDX3. The RQDX2 works well with my RX50 floppy drive, but I have no compatible RD51/RD52 disk. The RQDX3 refuses to cooperate with the MicroVAX I (don't know who's fault it is). Trying to boot the MicroVAX I diagnostics or VMS Standalone Backup from RX50s fails / hangs. DEC said in Micronote #43: "There are no diagnostics that are available for the RQDX3 on a MicroVAX I that is the only reason that the RQDX3 is not supportted on a MicroVAX I." Maybe that is not true for a MicroVAX I with an older Microcode revision? My MicroVAX I has Microcode Rev. 5 / Hardware Rev. 1 Anyone out there still running a MicroVAX I for fun or remembering troubles of that kind? Any hints / help welcome! (Especially donations of RD51 or RD52 disks ;-)) I'd really like to have my MicroVAX I running (rather: slow pacing) again! Regards Ulli