Mercedes shift problem

Hello, our 2012 mercedes 2660 stumbles when shifting from 4th to 3rd and 8th to 7th and sometimes 7th to 8th, any advice? The buzzer sounds and sometimes it finds the gear and sometimes neutral. Thank you in advance.

I suspect that it would benefit from you doing a gearbox “teach in”, this sounds like witchcraft but is in fact a recognised Mercedes thing. It’s been many years since I’ve done one but the manual will tell you how to do it. Given the vehicles age it’s doubtful you still have a manual so a trawl of you tube should help instead.

We have done both the short and the longer teach in several times, but doesnt seem to doo much. After we did the teach in the only gs code that comes in is 05

Ah sorry, unfortunately that was the extent of my expertise. Good luck.