Hello Ian. From your description it sounds as if you are on the right lines. Electrical insulation if required will need a thin piece of plastic or tufnol at some point to form a break. If you are worried about any detrimental effect on the magnetic operation I'd suggest using brass for most of the metal parts.

Tufnol used to be made from layers of cotton cloth impregnated with phenolic resin, and is a useful rigid insulator that is suitably "period".

To clean contact points I recommend a diamond spatula (fine grade) which are available from Farnell etc. They are pricey at about £10 each but will last for years.

Location: New Forest

Many thanks John for your response. On closer inspection today found that the little finger was in fact brass not steel, very strange as I have never seen brass corrode to resemble rusty steel.Perhaps intergranular corrosion because of an impurity in the manufacturing process of the brass.
I was able to beef up the brass as it wasn't actually broken just quite bendy.
The position is now: as soon as I increase engine speed contacts close and as revs die contacts open again. Rev engine contacts close no charge no matter how high the revs. Switch lights on with engine running fast,higher than normal discharge shown.
From this I deduce ammeter working and cutout working but dynamo suspect (fuse not blown).
Question now is could it be possible for the dynamo to be burnt out when the points didn't shut because the gap was too big to be pulled in by the magnetism?
Everything has been working fine before.

Location: Bristol

Happily your CF1 is now operating correctly in the electromagnetic dept. but, are the contacts clean and making effective contact when the cut-out operates?? If not, you will get zero charge.

Ian Mc.

Location: Shropshire

I'm not an expert on electrics but I don't think the cutout contacts would close if the dynamo was not doing something.

Location: Shropshire

Thanks Jim and Ian, that's what I thought the fact that it closes must mean it's working.Ian I did clean the points, maybe they look closed but aren't, maybe riding on my repair. Too cold and dark in the garage tonight and club spares shed in the morning so will have another look tomorrow afternoon. Plan is a mirror in the car to see the ammeter and put a screwdriver across the points when they close. Cheers Ian

Location: Bristol

Had another go this afternoon, on close inspection points looked closed with the naked eye. Shone a torch upwards directly under the points and there was the problem, points not closed by a gap no thicker than a human hair. Now sorted and all back in working condition. Really pleased I didn't have to resort to my fix with the pillar idea as it meant drilling an original part, not something I would do unless there was no other way out.

Some may find this useful sorry it's a F*rd site but good all the same.
http://modelabasics.com/Cutout.htm

Thanks again for your help guys. Ian

Location: Bristol

The F**d site is excellent for the illustrations etc. Thanks Ian

Location: Near M1 Motorway Jtn 28