MF CHORUS | I just got my MF-Chorus and there is no effect! Should I return the pedal?

No, there is a good chance that the effect is in Stereo mode, causing it to function abnormally with a standard ¼” audio cable in the output. To correct this is simple, just remove the screws holding the rubber feet and bottom panel to the pedal and check the small switch near the battery compartment. There are markings on the board indicating Mono and Stereo, so make sure that your switch is set to Mono unless you are using a stereo ¼” cable.