How to troubleshoot if some of your keys are not triggering on PC75
PC75 uses a 1.5mm thick polycarbonate plate. The plate and the PCBa board are fixed through switches solely without any screws to achieve flex during typing. Note the polycarbonate plate is soft and elastic. And the additional plate foam and switch pad has extended the thickness for the core portion of the keyboard, which will result in additional squeeze during transportation, and cause a few switches to be pushed out of the sockets, causing improper contact and not allowing the key to be triggered.
If this happens, please dissemble the keyboard to check whether the non-triggering switches are installed properly to the sockets. If it fell off, please push the PCBa board to ensure the switch pins are fully connected to the sockets.