Hi, have finished the repairs to my turn switch successfully. as mentioned the two rollers were each worn through completely on one side, so I machined new ones out of brass. The measurements for the rollers are 3mm ID x 4mm OD x 5mm long if others wish to do this.
One of the rivets holding the roller arms had let go on the top as is common. I was not successful in locating the wire drill and tap mentioned in an earlier post, in fact in the town that I live no one could supply machine screws smaller than 3mm or 1/8".
I decided I would have to use a 3mm screw but didn't want the roller arm to run on a thead as it would soon wear down. I drilled and tapped the casing 3mm but only used the taper and intermediate taps to keep the thread fairly tight in the casing.
A 3mm cap screw, 50mm long, was then purchased and I used a split 3mm die and gradually extended the thread down the shank until it left just enough unthreaded shank under the head to allow for the roller arm thickness and a tiny bit of end clearance. This takes quite a bit of patience and trial. (The split die was gradually tightened over 3 or so runs so as to get a good thread profile)
The head of the cap screw was then ground down so that it would end up just below the die cast rib, in the casing, and thus not foul the other moving parts of the switch when it was reassembled. (it ends up about 1mm thick)
The roller arm was then mounted onto the cap screw which was then screwed into the casing by hand and when the threaded end cleared the casing on the other side two 3mm nuts were locked up against each other and used to finally tighten the cap screw into position.
It was not possible to use loctite in this operation but the cap screw tightened up well against the casing at the end of the thread.(you could leave the end of the thread proud and peen it over if you wished, but be sure to mount a piece of steel in a vice to support the ground end of the cap screw if you do this) The surplus thread was then cut off with a junior hacksaw.
I also took the opportunity to ressurect the flash function for the headlights as the wires had been disconnected in the bakelite plug under the dash. Thanks to earlier posts this was easy.