Tony already addressed the cleaning issues quite well.
There's one thing I'd add (unless tony did and I missed it)....
The HP manuals for most of the 79xx series drives says to use tape to clean
up particles that have accumulated on the hub/spindle, positioner rails, and
even just anywhere inside the case were particles have built up (typically
metal).
I found that putting on the tape and pulling it up did a great job myself.
Jay West