I have a Stereo Poly Chorus (24V) that says “POLY CHORUS EC-7000 REV_D” and “4-19-2004” on the PCB.

The Double Track and Chorus modes still work fine, but recently the Flange and Filter Matrix modes stopped working. If I set the pedal to either Flange or Filter Matrix the signal sounds like when the pedal is not enabled at all.

Does this sounds like a certain defective component? Is there something specific I should be measuring? I’m no electronics expert, but willing to learn. I opened the pedal and measured the resistances for the four positions of the mode selector and that seems fine.