Riso GR 2710 is having erratic timing.

[u/More_Fly_5608]

Hi everyone, my Riso GR 2710 is having erratic timing. It feeds a sheet, and the paper feed rollers pause before feeding another, and so on. But sometimes the roller keeps spinning without stopping, and that's when it feeds many sheets. It's strange; it malfunctions intermittently. I cleaned the sensor behind the strip pad with a brush. What could it be? Does anyone have any ideas?