I picked up a HP 4145A that has a 5.25" floppy drive with the system on it, a couple of things spring to mind...
I wonder if anyone else has one and what software version you have and if anyone knows what the most up-to-date version was? Mine is revision A05.
As the 4145A is pretty much the same machine, only with a 3.5" drive, it would be interesting to try the 4145B software on it.
Ultimately I think I would like to replace the drive completely with a floppy emulator for reliability.