Thank you to everyone who commented on this string. I ordered replacement rollers that were 3D printed and they were significantly sharper than the worn out ones and I realized that some of my old ones were broken. I replaced all the rollers, gave it a clean paint job, a new belt, and reassembled it before tightening the screws on the back. It feels really snug and I think my problems fixed! I hope this thing holds out for another 20 years!