Kuroneko YZ looked to scavenging a hop-up from another AEG to fix the S&T UMP9 with a broken hop-up in part 1 in this custom project... "The HOP chamber part of the S&T standard electric gun [H&K UMP9 (Sports Line)] was damaged, so I used a set of HOP chambers for Marui G36 made by SHS. Repaired! I was happy to be able to use it smoothly with a little processing."