Liugong 856 loader won't shift

I'm renting a Liugong 856 series wheel loader from a friend. It's known to act up on the shifting. It's the electronic shift on the joystick. Has a clutch button on the front. It will be in gear and jump into neutral randomly. Its a pain sometimes as you mess with it and it will shift back in gear and then jump back to neutral. I put new batteries in it thinking it was low voltage, and it seemed to work better but still had random issues. Any ideas?

Which Type of transmission and TCU is fitted?
ZF WG?? EST ??

ZF

Hi star&b,
this is the famous push button shifter ERGO2 from ZF. Attached to a TCU EST25 or so. With a transmission 4WG180 or 200 underneath? See wiring attached.
Th micro switches sometimes lose contact and TCU switches to neutral.
The micro switches should be available worldwide.
Here an example in Germany.
https://www.conrad.de/de/p/zf-mikro...gXk-Ivd-lq4cAqx20NPAAC7_HBhsGiwwaAi7xEALw_wcB

Ok thank you so much. I will dig into it and let you know what we find.