You have two options for connecting chuff with the ERR stuff. I would verify where the cherry switches are connected. They could be wired to the CC board or directly to the sound board like your diagram. Sort of looks like you hooked up the reed/magnets to the sound board judging by the photo. You certainly don’t want both chuff inputs on both boards being used.
I’d try to fix the cherry switches in any case instead of the tender wheel setup. Continuity test them and verify the wiring through the 2/4 chuff selector switch. I have an L1s Mikado with this setup. Can’t remember what board they used for chuff though.
