Haven’t spent much time with this thing but you can find pictures below and here’s a first PDF modding guide (most mods would also work for 909/Steda/RE-909 etc.). Thanks for reading, thanks to the gearheads at modwiggler, gearspace, and sequencer.de!
-read T42 (not T24) for Hat VCA
-for hat dirtifier rather use clap noise instead of system noise since the latter introduces a tad bleed on bd/toms
You’ll find a playlist of somewhat hastily recorded mods (some crackles here and there) here: https://soundcloud.com/uibkmedan/sets/rd9_modifications.
And some pictures for your own analysis/delectation (never mind the odd additional cable or cap wired in by me):