If the analog delay chip is the Reticon SAD512 in the Micro Chorus and a Reticon SAD1024 in the others, the parts are not in production any more. The only easy options are cannibalizing another box that contains one, finding a leftover one, or hacking in one of the Panasonic MN3xxx series delay chips. This hack is almost certainly possible, but I have not seen one fixed this way yet. There are still some stocks of them remaining, but they will become harder and harder to get. This is not a task for the weekend pedal fixer, though, as you need to understand the circuits to know what to change.
First step is to look at the pot that is rotated when the pedal is moved.
This MAY cure it. If the pot is sealed, no holes into the interior, you may have to replace it. The manufacturer may have the actual part with the little gear, saving you a LOT of time and effort. If not, it is possible to get a new, same value pot and cut the shaft to length, drill a little hole for the pin that keeps the gear from slipping on the shaft, and reassembling. This requires some significant mechanical aptitude, though.