Good call! Per my very DIY testing, looks like it’s a 3/4” quarter twenty. In case anybody else has the same issue: gonna order this from Amazon and give it a shot https://www.amazon.com/20-Thumb-Screw-Stainless-Steel/dp/B09G92YYCM/ref=mp_s_a_1_3?adgrpid=109413341268&hvadid=580883111648&hvdev=m&hvlocphy=9032950&hvnetw=g&hvqmt=b&hvrand=14879091605203541678&hvtargid=kwd-761408404232&hydadcr=14652_13386744&keywords=1%2F4-20+thumb+screws&qid=1680231452&sr=8-3