Reopened the ST, and managed to get the RF shield off this time. Turns out you just need to slide the board out. I opened it thinking I’d remove the Tweety stereo mod since there was some nasty feedback on the audio out. Turns out the mod is glued to the board! I found the source of the feedback at least, the cable that taps into the sound chip was falling off. Everything else looks good, so I think I won’t have to take it apart again until the floppy drive needs service