I have one, Leon. The player is Charles Hollacher. Up until today, mine was the only one I'd ever seen.
The Service Candy company is somehow related to Henry Johnson Confectioners, as the Alameda 2785 phone number was also the phone number of the Henry Johnson Wholesale Confectioners company.
Additionally, although virtually ALL the Henry Johnson back stamps are purple on these blank-backed E121s (
), I have acquired three with green back stamps and the Henry Johnson Confectioners company names. They are certainly authentic, but use a typeface that is different from the traditional Henry Johnson stamp but similar to the Service Candy.
I've had these four cards for a couple of years now, and had come up with the hypothesis that Service Candy was a retail brand name of the candy produced by Henry Johnson. I have absolutely no proof of this, it's just a hypothesis.
BTW, your Service Candy stamp is even darker and easier to read than mine.
-Al