One of the first additions I did to the Genesis after I got my first CCD camera in 2006 was to motorize the focuser. At the time there was no European company that made a motor focus, so I had to purchase a ROBOFOCUS from the US.
This worked fine at first, but I was never too happy with the build quality of the controller. It became intermittent after a time and I traced the problem to be within the quartz crystal which provided the 'clock' for the PIC chip. Simply tapping the case of the crystal could generate the fault. At first I thought the problem may have been with a 'dry joint' on the PCB in the control box, but it was the crystal itself that was faulty!