The derailer. Note 3563L's position while the RD is under tension from the chain.



Careful persuasion removes 3563L from the top nut. It is imperative for safety (and to keep 3563L from flying into your face) to turn 3876 clockwise so that 3563L's tab is not resting against the derailer body. This is assuming an RD that is working correctly, unlike Suncake's SLJ:



As Suncake suspected, 3561 is supposed to have flats on either side, allowing the user to install 3563L by turning 3876 clockwise, thereby tensioning the spring.



If none of this makes sense, this video should make it crystal clear:


Suncake, please PM me, and I'll refund the cost of the parts plus the shipping back to me. Please keep the FD. I'd offer you a replacement 3561, but I'm not sure I can pull a spare SLJ out of nowhere . According to Robert's pages, it appears as if the part was common only to the LJ 1000, LJ 2000, and SLJ 5000/5001.

That said, is there a possibility that someone stuck a #3562 in place of a 3561 on Suncake's RD?

-Kurt