The Roland EP-7 is quite light and shows the same behavior after a while... values jumping all around...XITE-1/4LIVE wrote: FC7 and EV-1 do. Those suckers move around w/o touching them due to their heavier build I suppose.
For the EP7, I think it could be corrosion , or bad contact somewhere due to how it is built or else (i don't think it is made to last very long those 20€ pedals) or the cable or.....