I've not had the "pleasure" of working on a 201 that is locked up, but did free up a 401 a couple of years ago. I used kerosene (unscented lamp oil from Walmart) and 90% alcohol to free it up. It was obvious that it was dried up oil, though. I would stay away from the alcohol with a black machine. I used strips of old t-shirts, twine, cotton balls, q-tips and anything I could find to clean away the gunk in any place that moved. I soaked up my excess kerosene with paper towels under the joint. I used forceps to get into the places I couldn't reach. All and all, it took 3 or 4 cleanings before everything freed up. Then, I started with oil.
Good luck.
bkay
edit: I have a gorgeous 15-91 that is locked up to do soon. It looks like it's never been used.
Last edited by bkay; 11-22-2021 at 05:38 AM.
Reason: Added thought