Hello, I am refitting an old D&M 6 Milling Machine and I'm having a very irritating problem.

Moving/Jogging Y- works fine, as does X-

Y- and X- together works fine.

The problem is occurring when I try to move X+ and then Y+ (or vice-versa)

So if I hit X+ and then Y+, Y+ will stall (high pitched noise) and will not move again until I move the opposite axis in the - direction (in this case I have to move X- for Y+ to work again).

Does this make sense at all? Does anyone have any idea what could be causing this? I feel like a signal is getting stuck or flipped but it's just beyond the grasp of my knowledge.

Would appreciate any advice you could provide.

Thanks
Dave