tb6560 controller problem

[Wayne B]

I bought a Chinese CNC 4030 a couple of years ago and have been using it without any real problem until recently when the controller board blew one axis controller.
I replaced it with the tb6560 3-axis controller and got it set up and working...BUT... it will only work at very low speeds, it's like it has no torque and is mossing steps even without any load on the machine (not cutting).
I've read through all settings and can't work out what is wrong. It is using the original Chinese Steppers but they worked fine with the old controller which was a lower current maximum.
Any help appreciated, thanks