Dating cts pots
The original MXR pots have a shaft sticking through the middle on the back of the pot and the numbering on the pots will usually start with MXR as they had them specially made.Also check for MEXICO on the switch, with a date code like 0329 = 2003 26th week Mexican switch.It is divided in four squares and usually under the battery.There should be a serial number sticker too, usually on the side of the battery.Finally, a word of caution: This method applies only to American made pots and not all potentiometer manufacturers subscribed to the EIA source code date.If the code does not fit the above criteria, don’t force it and skew your dating results.The ones from California do not have these stickers.
I have owned this since 1990 and always believed it to be from 1971 or 1972. Or it is a 137 = CTS pot 35 = 35 the week , 2 = 1972Look there; // Info Your guitar was made at the Fullerton Plant (Fender - CBS Era), USAin the Year(s): 1971Some contradiction here but nothing unusual.
Here are the pots in this pedal, new ALPHA pots instead of original CTS pots.
The original pots are the only way to date an MXR pedal, so this pedal is not very valuable even if someone could get it working, as the date codes and pots are gone. I have also seen these "NOS" pedals turn up with pots with the last digits as 0318 which means 2003 18th week.
MXR used USA made Carling switches until very late, then may have used some mexican ones.
Original Mexican MXR switches should have UND LAB marking on it and some voltage rating, not the date code. Notice the lousy soldering and that the board had several broken traces, which was probably why MXR never used it and probably discarded it.