Scanner life

I have a Sharp AL-1641CS laser all-in-one. It creaks and it groans
when it scans, but there doesn't seem to be anything wrong with it.
It's a good scanner that's a bit clunky. But I'm wondering what the
lifespan of a scanner is. How many pages should I expect to scan
before something breaks? I'm scanning around 500 pages a week.

SB