The main problem is simply the spindle driver electronics and motor. In my experience the other electronics are robust. I think one other user tried a different BLDC spindle driver to some success but as I recall it was expensive and I'm not sure how it ultimately worked out for him. I converted mine to an AC motor with VFD. I ended up making a custom board to interface the VFD with the existing electronics for a seamless integration. Hit me up, I'm happy to help.