ahh thats the old style wagner head
theres 2 types of heads
the old style head which is in a square black box marked wagner
this used a few microswitches soldered to a board that were actuated by a cam mounted to the twistgrips
i dont ever remember seeing these old style heads with potentiometers ive only seen them with the switch boards (older linde EGU-20's made by still)

the newer linde EGU20-02's come with a more ergonomic styled head with a potentiometer and switches soldered on a board (you cant see or adjust it you can only replace the board)

if you have the newer style you most likely will have to change the setting labeled "throttle type" as still constantly changes the pot to 0-5v or a 5-0 volt and it almost always doenst match what you had in before
youll need a handset or the "Curtis PC Programmer" and its interface


both styles i believe have the emergency reverse switch soldered to the same board in both cases

the new board the switches are very small and the pot is encased in a black housing that the twistgrip shaft runs through