I bought a lab stirrer for basically nothing, knowing full-well it was probably broken - and it is! but I think it might be salvageable. It's a Euro-st p cv. When I turn it on, the display lights up as intended. I can control the motor speed with a knob, and the display shows the RPM settings, so that's all good. But, the motor doesn't turn. When I increase the RPM to about halfway the maximum range, The unit displays an error-4, which is an over-torque protection. turning the power off and on (and turning the knob back) resets the unit. The motor shaft spins freely so it isn't actually over-torquing. Is there something obvious that comes to mind that might be wrong? I think (and hope) it has something to do with the power-board. Off-topic: can anyone tell me why these things are so ridiculously expensive? A new unit costs like $3000. There's nothing inside that would warrant a price even one tenth of that - all standard components.