Hi - I would appreciate some advice. The x and y axes steppers on My Boxford 190 VMC whine and jerk and stall, but only at a feed rate of around 800 mm per min (say 750 to 850) - all other feed rates have no problem and run smoothly. The motors and drivers are originals with a breakout board added. Can anyone advise where I should start to diagnose the issue? Cheers and thanks in advance. TheMule