An "optical rotary encoder"? I doubt it. I bet it's a mechanical rotary encoder. And that it randomly jumps means their code for reading the encoder sucks. Some

An "optical rotary encoder"? I doubt it. I bet it's a mechanical rotary encoder. And that it randomly jumps means their code for reading the encoder sucks. Something like that should not happen if properly implemented. I will take a rotary encoder over a potentiometer every time.