I get the impression that g1 x10 works just fine? Ditto g1 y10?
IF so, then all the electronics, the wiring and the motors are just fine. If they were not, those instructions would not work properly.
If it is only a jog command which goes wrong, then the problem lies between the keyboard and the Mach keyboard input - that part of Mach which collects the key strokes. If the Hotkeys photo is still valid, then I can only suggest reinstalling Mach3, preferably (VERY preferably) version .062
Cheers
Roger