Steve, glad you found the problem and figured out that the Mk III aren't the mechanical nightmares they're touted to be.
As far as future cleaning goes, 22RF ammo is notorious for being kinda dirty, so I would recommend using oils sparingly. Better bet is to choose one of the new "dry" lubes, like Hornady One-Shot, Hoppe's equivalent, or others of that ilk. I've found that going to those, greatly increased the time between cleanings. FWIW, I use my Mk III for bullseye and don't have to tear down and clean except after about 1500-2000 rounds.