CAT 924 G transmission problems

Hello,

yesterday I got some work to do with my cat 924G and I noticed that a new problem is arriving. 3 or 4 times the transmission did nothing, when the gear was engaged. After trying many times forward & reverse it returned to normal life again. Does anyone knows, which steps should I take? In my oppinion it looks like to be an electrical contact problem.

Thanks for helping advice
Gerry