I removed all the bits from the inside of the front passenger door to have a look at the faulty window and all I can see is the white plastic lump the motor fits onto making the most horrible grinding and screeching noises whilst jumping around a bit....

I'm no expert, but to me it looks and sounds a bit f*cked.
I'm sure I can remove said motor/window assembly to replace the broken part(s) - its just putting it back which I may find a bit tricky - so any pointers??