Study this photo carefully
This course builds upon the foundational knowledge of the various Rickenbacker pickups that you acquired during your undergraduate studies. These include the Toaster, Hi-Gain, and Humbucker pickups, among others.
Let’s begin our discussion by examining a unique topic: Toaster pickup "dots." Who would like to volunteer to explain to the class what we’re looking at here? Q1: What caused the dots (see the corners on the toaster's black strips, where the bread would go) - 1 point. Q2: What years had the 'true' dots' - 1 point. Bonus: When did the the repro dots appear? 2 points.
From @haulinkraut:
These are bakelite bobbin mold impressions. 1957-1964. Repro(fake) dots started in 2002. These dots were introduced as part of the C series development.
There is a bit of variation and nuance. To my eyes on all the ones I have seen from the 50s and 60s with mold impressions, the outer circle is raised and the center recesses. It looks to be a mold flashing around the circumference. And then the center of the circle looks like where a mold plug and placed in and the flashing is from the seam. One thing also to note is there were transitional toaster bobbins that came along in 1964 for the Rose Morris that used paxolin phenolic bobbin with a vacuum formed plastic top piece for trim. These bobbins fell in line with the time period that mold impressions disappeared in 1964. And then after that the bakelite bobbins were back, but did not have mold circles. Not sure if the mold was replaced, modded to omit the circles? Or if the bobbins just had a post casting process added to sand the circles away? Or perhaps the vacuum formed RM covers over the bobbins were to take the place while the mold was out of order to get fixed remade? Or maybe just due to the sheer volume of order between Export models and US market.