- All vintage USA Big Muffs have source-date codes stamped on the underside of the potentiometer cans, or “pots”.
The pots are what the knobs are mounted to, essentally manually adjustable resisitors that control the voltage across a circuit.
In the second string of numbers, the first three numbers are a code identifying the manufacturer.
The next two numbers after the manufacturer number are the year, and the last two numbers are the week of the year the pots were made.
When I replace pick ups I put a new set of pots on it. I do an install that is cleaner than the ones that came new on the guitar.
If they need replaced just do it they are about $8.00 each.
My discussed pot in this thread is R137yyww = R1378131 = 1981/31st week (R137 = mfg) Typically, before 1981, you will see "wwyd" = week/year/day of week Example on a 1970s Stratocaster neck butt date "0903-2455" 09=Stratocaster 03=Maple Neck 24=24th Week 5=1975 5=Friday What I've been understanding, serial numbers are only an indication of a year, but could be five years off, like my Telecaster. I know nothing about the Lipstick pickups Heard of them and recently saw a Tele with a Lipstick on the neck pickup Kevin, my thing is this.