so i have a dunlop slash wah pedal and it's been working great until yesterday. the problem is when i turn it on i can't hear anything, only after a few seconds it starts to work but only with a fade in, then it stops again, and sometimes it sounds like something is lowering the gain between the pedal and amp and when i turn it off everything sounds like it should be, so it's not the cable. it does the same thing with batteries too. i tried to reverse cables, to change them, i don't really know what to do now.
So to confirm - you changed the cables (not just swapped them), and used different power supplies and still get the same response? Yeah, then it's probably internal. Are you good with a meter and soldering iron? (finding and fixing a bad solder joint or swapping a component may not be too difficult...)