The majority parts that wear out are in the toner cartridges, there is a plastic blade that scrapes off the excess toner off of the imaging drum, this blade can wear or tear and cause toner streaking. The other part that goes out is the fuser, it melts the toner and presses it onto the paper. After those items the things to worry about are the paper pickup rollers, they wear out but can be cleaned with an alcohol pad or lint free cloth with a bit of isopropyl alcohol and the rollers will work for a while. I believe there are maintenance kits available for this model, the kit has a fuser and the paper pickup rollers.
The old LaserJet II was a durable model, I worked on one that was improperly packed onto a truck that got blown over in a wind storm. The interior was a mess with toner and the bottom was dented badly. All I had to do was clean up the spilled toner and push the dent back down to get the printer to work.