Summicron 11818 (Rigid) focus quirk
I recently picked up another chrome Summicron Rigid (11818). The seller described it as having been CLA'd by DAG. It's a lovely example, near mint, no scratches, and focus is buttery smooth -- 99.9 percent of the time. Every once in a while the focus will halt or get stuck for a moment, but just a moment. This happens quite rarely and I could sit for 10 minutes turning the focus of the lens without it happening. In a full day of shooting it happens once or twice. Any ideas what the problem may be?