When I did in-house repair of micro-computers that were ties to our laboratory measurements, the failures fell roughly into the following categories:
1. Power conditioning - I used OneAC power conditioners with an Isobar. Got like 18 years out of a Mac computer with just a floppy and fan failure.
2. Mechanical - Dust. Mainly caused fan failure. Fixed with PM's
3. Mechanical Wear - 8" floppies, regular floppies, fans.
4. Heat - The corollary of dust.
Once I did #1 which was about $1000 down time really dropped. The conditioning was implemented as the company (Digital Equipment Corp) went under.
One vacuum gage we had many of always had capacitor failures about every 4 or 5 years. It was really environmental. Another Sorenson power supply which we had many of basically needed a re-cap at the 10 or 15 year mark.
So, temperature, power supply voltage and ripple are really good things to monitor.
Crystalfontz and one of the other ones was just the display and/or buttons and everything else to be able to drop it into a drive bay, You get to roll your own,
While your at it connect it to ethernet with SMNT traps and or email/txt messages.