Help w/ HP 88780 Tape Drive (corrected email).

*sorry a copy went out prematurely... So I got my hands on an HP 88780 1/2" Tape Drive from list Member Mark (Thanks!). The drive physically looks to be in good shape but was pretty dirty when I got it. I've cleaned up the drive and powered it up. The good news: The drive powers up. Initially I had trouble getting it to load a tape but that seems to have been resolved. The BOT, EOT sensors are good and the basic drive mechanism (motor, eject, etc.) seem to be working. The bad news: Some of the front panel buttons are not working. Running test 72 shows failure in the unload/rewind and online buttons. Luckily it seems to be a mechanical problem. If I short the switch on the circuit board then the test passes. The switches are mechanical push buttons that are soldered on so should be easy to replace. Anyone know of a good or OEM equivalent replacement? If need be I can get pictures of the buttons off the PCB. The worse news: The tape drive will not read/write. I ran test 01 which per the service manual does a full general checkout of the drive. The test is a conglomerate of other test routines. It fails when it tries to run test 177 (Buffer Write Density ID). This is where I am currently stock and need advice on how to proceed. Any help is appreciated. TIA -Ali