Kontrol Z2 - XF reverse & curve not working

Hey all! After searching for quite a bit, I was able to find a Z2 in almost mint condition. After quite some testing in the recent days I have to say it works like a charm with TP3 and is a lot of fun!

However, I found two switches without function: The XF Reverse toggle switch as well as the XF curve knob. Once I move the toggle switch, nothing happens and „XF Reverse“ also doesn‘t light up in the LED display.

Peronally for me it‘s not the biggest issue, since I rarely used the reverse function on my old mixer. The adjustable curve would be nice to have but also not something which bothers me a lot as long as the other features work like they do.

Anyways, did somebody have a similar issue with the switches or does anybody have an idea of how to fix it? Any help would be much appreciated!