Hi iv just picked up a 60/40 just the same as yours but it has the all in one board. Iv had problems with my motors as well. if i set the tuning to what they say in the set up sheet, Then run them at 100 jog they jam when i running them up and down. they run for about 50mm then jam. I have set the motor tuning to half what they say and they seem to run ok. so that would be 400 1000 100 . Iy runs slower but no horrible crunching. This is my first cnc so i dont know enuf to know if this is ok but its running.