MGF Wiper motor noisy

My wiper motor packed in after becoming noisy the other day just when I needed it the most. A second hand replacement is on its way with the large grey plug which is different to the TF having a smaller plug.
I can do the swap over as it seems relatively straight forward following the excellent "how to", but I am just wandering if its feasible to strip down the motor to see what the problem is.
I have had the motor cover off and glad to say there was no water residue inside; so thinking there must be a failed bearing or worn gear inside the sealed casing. I would be interested to know if anyone has already had a go at this.....I would rather repair it then bin it.

I stripped my old motor, but it was obvious what the problem was. It was full of brown sludge!