I´m leaning to the problem being in the "driving logic device, A10", the board with most of the I/O connections to the machine. This since all the time(also during fault) the board lights up the forward resp reverse LED-diodes when I depress the directions buttons on the joystick. At the moment the fault seems to follow cabin temperature(or board temperature)...
The fault could I guess be in the Susmic drive controller also but thats the one I once exchanged already so hoping I get away with something a bit cheeper this time...
The phenomena with setting on the work breaks in an instance I have so far avoided simply by disengaging the automatic work break function all together, with the corresponding switch. I´ll have to check the schematics to see which device rule over that function...