I have 8 of the X scan Plus units in my venue and they have been subjected to all manner of manner of misuse! They get left on for days on end, bashed my promoters, Dj's and people hitting them whilst dancing. They get clogged by smoke, the fogger and dust and other rubbish. However they have never stopped working, infact they work better than lights three times their price.
The only thing we do is clean the outside of the unit, the lense on the top and the mirror and then the gobo's will come back as sharp as ever. If you do get a smashed mirror, just use the mirror out of a ladies compact case. We buy them from the local chemist for £1.99 and they make a great fix.
The only common fault we have had with all of them is that the adjustable lense casing cracks and the lense will fall out. We think the plastic goes brittle with age and the C spring inside plastic ring top forces the plastic open and makes it crack. Other than that we had have no problem. The other minor problem is that one of the fittings always panned the opposite direction to all the others but this was a bad DMX lead.
One good thing with these lights are that if your computer fails the lights take over and will work in auto mode.