The router lift had lost a couple of stop pins that held the lock in place. You could overdrive the lock and keep spinning it. The pins had backed out, and were eventually sucked up in a vacuum, brushed out, whatever. I ordered new pins and put them in yesterday, so the lift lock is perfectly functional again.
Just in time for the new table to arrive today. I will see about transferring the Jessem Lift over to the new table.