Take it out and give it a clean, its not a sealed unit, theres a how to somewhere i'll go dig it out for you

 

Sorry for delay in replying. i will take it apart next weekend . many thanks.

 

A small torx or hex is all you need, split the casing from the motor and see how it looks inside, probably needs a good clean out with WD40 to get rid of the water/gunge and then you will see, if when you open it there is no dirt or much in there, then your brushes (I think that's the name in English) may be on their way south, but luckily a replacement motor is not expensive, plenty on Ebay and even on offer from other members I have no doubt....

 

Mine sounds like I'm stranfgling a cat. I have a spare one I got off another Rover, not an MGF. It looked the same.

I did take mine apart twice, cleaned it, soaked it with WD40, regreased it and still makes same noise. I thought I'd fix it if it went... that was last year and the poor old beggar still works!

 

I will be receiving a replacement one in the post shortly, once that is fitted I will be stripping down the old one to see if I can cure the noise.
The motor rotor is easy to get to, it is just 3 torx screws, I have already took cover off and drained and cleaned it but it made no difference so my plan is to take the wiper motor gearbox apart which appears to be held together by rivets to see if the gearbox is repairable because that seems to be where the noise is coming from.

I will keep you updated, should be this weekend with a bit of luck.

 

I took the motor assembly apart on Saturday and the gearbox is not at fault it must be the rotor that makes the horrible grinding noise, so in my case the wiper motor is not repairable, thankfully I managed to find a quiet replacement.

 

the noise comes from the ball bearing in the motor at the gearbox end
the water seeps past the bearing causeing it to rust hence the noise and water in the bottom of the casing i tried to replace the bearing but couldnt get the rotor out must be a shrink fit.