Thanks a gazillion, "5DMKII", for your very explicit warning/instruction about this product! Based on your review, I decided to chance it.
Sure enough, out of the box the transmitter was non-operational (even though the pilot light would shine when triggered). I pulled the battery. (God, there has GOT to be a simpler way to replace this 23A than completely disassembling the blooming transmitter! No? No?!! I assume that little length of unattached black wire sitting in there is the antenna.). When I tested the OEM battery, it looked to be on the low end of OK.
But I replaced it with a fresh 23A and tested the transmitter (by pressing the little button switch on the teeny-tiny circuit board before I even closed up the case). Bingo! Works like a charm now. So out comes the battery, closed up the case, and hope to make use of this set in a fairly complicated photo shoot later this month. (BTW, polarity marks appear to be missing, and I hadn't noticed orientation when removing the OEM battery. Since it worked, the negative pole of the little battery goes to the spring-loaded end of the battery holder. Your results may vary.)
So, .... I'll be carrying a fresh battery or two, and a #0 phillips head screwdriver -- and be praying I don't drop the screw on the floor when placing/replacing the 23As. OK, maybe I'll also carry a small magnet so I can hopefully retrieve the screw. Sigh!
Sir, in your experience, about how long does the 23A battery last in use? And I assume the 2 AAs in the receivers are a bit longer-lived? Thanks again for your thorough review!