Hard to tell what your piece of glass is, possibly a cover for a led array or mirror.
I'll concur on the HP printers, not really fond of the 1xxx printers, but most others give very few problems and are very easy to service. Seem to last forever, and on that note, if you're willing to take a bit of a chance there are always several good used units -- either off lease or from bankruptcies -- available on eBay in the higher level. Look for a seller with good feedback and read all of the fine print. I've bought several HP laserjet 5's (which is probably the most solid printer ever built in the range) and 8000's that way with minimal problems. Again, it's always a gamble, I've had good luck, but it's your buck.
Another good option would be the Oki lasers. Generally well built (not quite as solid as the HP) and software compatible. You can generally get a few more options for the same price. Parts are readily avaible and the machines are built to be serviced.
What ever you do, stay away from Brother printers in the future. You've actually been lucky. Generally see software/driver problems, and servicing is a problem. Doubt you could get someone to service out of warranty for a reasonable price. Generally built to be used for a while then landfilled.