Very happy to report that this is resolved! The solution was, as
wcanonw, Copylady72, Jpiek and others suggested, to pull the IR-2020 laser unit and clean the glass manually. I was looking for other fixes because I (mistakenly) assumed that it was clean after using the supplied cleaning tool. The printer is now being used again and we have our fingers crossed it can limp across the finish line in January when it will be replaced by a newer model arriving on our cargo vessel. You can see the new results after cleaning from the attached test page.
This video was also helpful to see the procedure being done:
YouTube
Thanks again to everyone who chimed in with advice. If anyone from this thread would like a postcard from McMurdo station, DM me your address and I'll drop one in the mail. In the meantime, enjoy this picture I took from a recent trip to the Lake Hoare field camp on the Antarctic mainland. Cheers!
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