Alright. I had another go at it. The gland cap does turn, though its not threaded. The fluid fitting actually goes through the cylinder barrel, and threads into the gland cap. So that fluid fitting had to be removed first, then the cap turns. I was then able to spin the cap to help the split retaining ring to uncoil from the groove. Once that was out of the way, it was pretty simple to tap it appart and remove the seals. Now I just need to match up the seals with replacments and put it all back together!
