Help with possibly broken control board

[Jottesman 0]

Hi there,

I have an Ultimaker 2 (With the E3D upgrade kit). Recently the stepper motor that runs the extruder has stopped working. It stared with clicking that appeared to be missed steps but is now completely haywire, sometimes emitting long high pitched tone when working, sometimes producing intermittent undesired movement.

I hoped that it was the stepper motor itself, however swapping to a different motor yielded the same result. I have also tied updating the firmware and later editing the firmware to use the stepper driver for the (Non-existent) second extruder, both to no avail.

I have two questions:

I wondered if there are any other possibilities I should explore before buying a new board entirely? (the board is the Ultimainboard rev2.1.1)

If I do need a new board, when can I find one, most places don't seem to stock the main board. Does anyone have any experience buying a new one?

Many thanks in advance