I'd also be interested in exploring the Delrin bushing. Randall, want to explain how you would go about obtaining and fabricating that bushing? That would be very helpful.
The Delrin originally came from MMC as a 3' length of 1.25" bar (previously bought for some other project). Not necessarily the best choice, just what I had handy.
https://www.mcmaster.com/?m=true#standard-acetal-homopolymer-rods/=zmgcqf
I measured the id of the tube, and the od of the shaft where it passed through the original felt, plus the length of the tube above the constricted portion. Then I machined a piece of Delrin to those dimensions. Delrin machines really easy if your tools are sharp. Have to keep the surface speed down though, or it melts and gets sticky. A coolant system would no doubt help that, but I don't have one. I started the hole with a series of twist drills, then finished with a boring bar held in the tool post.
I wasn't sure how much clearance to leave so I started with none on the theory that the Delrin would compress slightly. That was too tight, so I went back to the lathe and took a couple of thousandths off the inside of the bushing. Since strict concentricity didn't seem critical here, and I only needed a very light cut; I just lightly clamped the bushing in the 3 jaw chuck (so it didn't distort much) and ran the boring bar through it again. (I also don't have a collet chuck, and setting up the 4 jaw to run concentric is too much like work.)
Sorry, I'm afraid that still isn't very helpful if you don't have a lathe available. I don't use mine enough to justify the cost (or the space it takes up), but it's a fun toy and occasionally useful.