Have you checked the set screw on the knob? Sounds like knob is pushed in to far and knob has friction with faceplate. If you loosen set screw pull knob back very slightly then tighten down set screw knob should move freely. I’m not familiar with your amp but have experienced this with some amps of my own.
Plinius repairs
Hi, I'm looking for a repair place/person hopefully in Florida if possible to repair the Plinius Hiato volume knob. I can turn the know by hand but it's hard, and when I use the remote to adjust the volume, the knob doesn't move at all. Thank you for your help.