Instead of "pushed all the way down", is it actually that some buttons activate when pressed, and some activate when released? That's to be expected if you have some buttons that have a hold function on them. The system needs to know whether you're holding the button or just pressing it, so it needs to wait for you to release the button before it can figure out what your intention is.
If you still need switches, the switches we sell on the website will work with any PBC/6X. However, on an older one like yours, you'll need to desolder the wires from the circuit board, then remove the switches. (Or cut the wires, remove the switches, and desolder the wires from the circuit board.) Then, cut the connector off the new switches, strip the ends of the wires and solder them to the circuit board.