There is no "pot" inside. The round dials are a mechanical calculator. Unscrew the knurled screw in the center and the whole calculator assembly just pops off. There is a lock pin the button on the top left moves so you can adjust the asa setting. Just line it back up with the hole in the bottom of the calculator when you replace the round assembly. My V is still working and I bought it brand new.... a long time ago.