EH 1307 Deluxe Memory Man with Squelch
EH 7550 - Deluxe Memory Man - 4 knobs - Red and Blue - Squelch switch - SAD1024 - Compander
I've seen quite a few of these but I haven't done a proper trace yet to confirm a match to the EH 7550 schematic.
SCHEMATIC:
Try the EH 7550 schematic. This is most likely the correct schematic for EH 1307.
Random note: The last EH1307 (no letter designator) I looked at had the intitals "DC" hand written on the solder side over the delay chips. I wonder is those are for "David Cockerell."