Clean or replace UP Mini extruder, and general service

I have an UP Mini that I bought 10 or 12 years ago. I never really used it lot after the first 6 months. My 9 year old son is now interested in creating things so I am getting it back into use.

I bought a fresh roll of PLA and started printing the parts for a model my son wants, and it has been going well. I am getting better results than I ever recall getting before (with ABS). But with just two parts left to print, the filament is no longer extruding, and the extruder is making a clicking/clunking noise when I try to extrude or withdraw.

I assume there is some kind of blockage, but I don’t know how to go about cleaning it. I can’t find most of the bits that came with printer.

So if anyone can help with

  1. How do I fix the immediate problem with the extruder?

  2. How do I do a general service of a machine that has been used maybe once in the past 6 years?

With a bit more searching I found some old posts about this issue, and without knowing what I’m doing i started unscrewing anything that moved. (If I wreck a 10-year-old machine it gives me an excuse to buy a new one.) I managed to clean the extruder and get it put back together, and my print is currently about 3 minutes from finishing.

I’d still like any advice about general servicing of the machine.