I live in Japan, and just bought a used Epson pm4000-PX,which corresponds to the 2200. Everything seems to work, except that on printout I get yellow/green horizontal bands at intervals of about a centimeter. Could this be due to something other than clogged nozzles?

I checked for reports of similar problems, but found nothing exactly the same. I noticed advice to turn off hi-speed printing, which I did, to no effect.

The ink levels indicator shows low levels, but not empty, but Clean Nozzles brings up a message that it can't be done without changing cartridges, but doesn't say which one.
I don't want to buy a whole new set of cartridges if the problem is more serious than that. What do you think?

First, run a print head alignment. You can do this via the printer driver software. Make sure the head is aligned properly. You'll need a few sheets of good quality photo paper to see the alignment lines clearly. Glossy or luster paper is fine.

Next, you should see which inks are low. You can again do this via the status monitor printer software, or you can look at the blinking red lights on the front of the printer, which indicate which of the 7 cartridges is low. Only those need to be replaced.

Eric

It does mean that cleaning nozzles cannot be completed witht the current amount of ink. You'll need to put new inks before cleaning. Use the status monitor to see which cartridges are low. Install cartridges one by one until you are allowed to perform nozzles cleaning.
Once you have done nozzles cleaning and heads alignment, you can put the "almost empty" cartridges (the ones you had to remove) back in your printer to print until they are really empty.