I removed some more transistors from the board, but I can't find data sheets for these (other than the two more STS 733s); I've tried searching for the text on the transistors and for combinations of various portions, not knowing what part refers to the part number, but haven't had any success.
One transistor was marked with R2001 C217, and another couple were marked with K 214 C2303 Y. Didn't find any data sheet results using datasheetarchive.com or google.
Also, is there any simple way of testing if an infra-red IC is functional?