A useful bit of information:
The Quantum 105S hard drives are what was found in SPARCstation 2s, and they have a manufacturing fault.
If your 105S when plugged in doesn't start to spin up, it's because the lubricating oil has gunked up or something, can't remember exactly. A few short sharp raps on the top will usually free it up and next time you plug it in it'll start up just fine.
Of course you'll probably want to change that disk anyway (100MB not being massive!) but they're good solid drives - I use mine as a boot disk for my SPARC 10.
