Intro and 9133D HDD

[JvZ]

MY first post here.

Been collecting a number of old HP computers and currently have 3 x 150s, 4 x 85s, 2 x 86s and a few HP-UX systems (712, 715, etc.). Started the restore on the 150s the last 2 weeks.

Also have a 9121D, 9122D and 9133D. (Also 3 x 9123s but don't have an 150II yet.) All the floppies required disassembly to clean and they all are now working except Drive B in the 9122.

My question is on the 9133D. The fault light stays on permanently, even though the floppy works and I can read and write to it from the 150. From the diags and tests it seems the ST-419 HDD is faulty, though it spins up and attempts a format.

Any ideas if I can drop in a "more modern" ST-506 drive (such as a ST-225) in this unit? I read what documentation I could find, but did not see anything.

Or, potentially, any ideas on resurrecting the ST-419?

Any help will be appreciated!