I do not have that exact system installed so I don't have an answer for you. Someone who knows will answer that question though.

I looked at the exploded view of parts in the instruction sheet and it appears that what I'm seeing is the gasket.

Yes, that is the plastic ring that the rings tighten against and if they are not then they tend slip easier.

I just got a quick reply from Barb at OE who said, "We added the nylon washer between the adjustment & locking ring to help prevent overtightening of the setting, which can cause the rings to become stuck. Try removing the nylon - it will create a 'firmer' lock on the setting. When removing the jar, you need only hold the adjustment ring - that is the only part the jar touches. Usually people have the opposite problem from yours - they used to overtighten the rings and that is why we added the nylon washer. You can remove the washer by removing the bottom screw, and washer, unthread the adjustment ring, remove the nylon washer, then replace the adjustment ring, washer & screw."

I'll try that and hope I don't get the other extreme of locked rings.

If you jam the rings then just whack around the lower ring with a small wood mallet or 1 1/2-2" diameter wood rod. They will promptly unlock.

Whoa, where would I hit it? Sounds a bit drastic.

On the lower ring.

Sorry for the slow uptake but hit directly/square on the adjustment ring? Not at an angle to force the ring to turn?

No, you just work around the ring and it comes loose.

OK, thanks, I think I've got it.