So, start by heating the steel m6 bolts which house the fan cradle on to the rad, chances are they have oxidised in the thread, heat helps removal.
Remove fan, m6 flanged nut, idealy replace this with a stainless steel of same spec.
Drill out the 3 rivets that hold the two motor housings together.
Prize apart using a small sharp flat screwdriver, as the housing is external it has a mastic to keep water out.
Open up the casings, and this is the result. Yo may need to replace or repack the bearing with grease, certainly the bearing exposed can dry up a tad, and using a small sharp blade you can prise out the bearing shield and inspect the bearing condition, bearing size is 6072 for the internal one, which usually remains good, but the external bearing is 607v, which has the removable shield.
You will also see the carbon brushes, which generally are easy to replace if required, but I doubt it.
Here are some pics,. Oh and dont forget the 3 very thin washers, one is spring steel, and the other are a type of low friction teflon,.these go against the exterior bearing on the inside of the domed shield.
I would like to post pics, of which I have , but it seems I have exceeded my upload quota, may be you folks can help?

 

Not exceeded your upload quota Bullroarer, just not approved as a member by an Admin yet. Yet to be approved members cannot post pictures - see link in my sig line. Be patient and it will happen.

Cheers, SB

 

Bullroarer, we have a waiting room, its called the saloon.

 

It happened bullroarer, you're good to go.

 

Thanks matey
Here goes.