OK...as an update to this thread, problem solved - but a different method...(
sorry about the links, but my attempts to post pictures failed for some reason)
Firstly, the Rover 400 wiper motor is located by 4 x M6 bolts all of which need to be removed & the cover is different, plastic now and no rivets - but bits of casting riveted over instead.
http://www.flickr.com/photos/harvey_s/5033176070/
I drilled through these with a 3.2mm drill to suit the self tappers I had, then chiseled off the heads - the next problem was that Rover have also glued the damn thing down and you need a very small screwdriver to get right under to prise it off without breaking it
http://www.flickr.com/photos/harvey_s/5033177240/
Then when you have got it off you see that rover have used a star clip with the strength of Satan! - don't even bother trying to get it off - it won't budge!
http://www.flickr.com/photos/harvey_s/5032558203/
Go around the other side and just drill it out with a 1/4" or 6.2mm bit.
then prise out the clip & remove the track disc...
In my case the contacts were fine...
http://www.flickr.com/photos/harvey_s/5033179626/in/photostream/
so I just cleaned out all the old grease and lightly regreased the tracks.
To reassemble you will need...
2 x M8 plain washers
1 x M6 pan head screw x about 15mm long
1 x M6 plain washer
1 x M6 Nyloc nut
The 2 M8 washers go where the star clip was, the screw is inserted through from this side and the plain washer & nyloc go on top...
http://www.flickr.com/photos/harvey_s/5032560943/in/set-72157625052213904/
otherwise its pretty much a the original guide and dunno why mine packed up because the contacts looked very good - but it all works nicely again now and thats the main thing
