Montys or Tri-supply will sell you good oil seals.
Thanks GPZ. The UK made seals which came from TMS are manufactured by Pioneer Weston (see pic), they go into the hole fine it's only when I tried to press them past the circlip groove that they caught and tore the outer rubber covering. I've got a couple more coming from a different supplier, I think they'll be identical so I'll look at chamfering the lower edge of the circlip slot slightly.Take a sharp tool and de-bur the edge of the seal hole, even with a tiny bit of chamfer. Then, carefully press in the new seal.
Hopefully to be clearer, the parts book isn't wrong, it's the current maker/commissioner of the switches:-The 1972 parts book is incorrect, it quotes 60-2133 which is the tapered thread switch.
... is specifically the 500's built from the second week of December 1968; Meriden appears to have been fitting NPS-thread switches and timing covers certainly by the time the date-code-format numbering started being used in October 1968, Meriden built 650's from October 1968 'til the first week of December 1968.those made after calendar December 1968 have parallel-thread (1/8”NPS) pressure switch holes
'Fraid I have to disagree with Andy on this occasion, it's whatever solder the PO used. The oldest Mk.4's are less than twenty years old; otoh, I reused a few original wires from the T160 loom (now 45 or 46 years old) in my first rewire (38 years old), I've stripped original Lucas looms from when they soldered bullet terminals (60-odd? years ago), one of my old Japanese bikes was 35 years old and had covered nearly 90K when it went to the breaker but I've worked on Japanese bikes that'd covered two and three times that mileage. I've only ever seen "Black wire disease" on a very few crappy PO-soldered joints.Boyer EI.
PO had soldered the connections at the stator plate
When I stripped the wires to remake the connection the copper strands were black and brittle,
The soldered connection or maybe it’s just a very old Micro MkIV system?
Have you checked the price of a new stator plate (if Bransden is still working )?had to cut the wires back about 3 inches to get to decent looking copper. On the stator plate itself I was limited by the very short wires but managed to get some improvement though not as good as I wanted.
Hope you haven't redone this? Ime, soldering connections like this is completely unnecessary and, as you've found, a pita when you need to remove the trigger unit. Fwiw:-PO had soldered the connections at the stator plate
Feel free Stuart!'Fraid I have to disagree with Andy on this occasion, it's whatever solder the PO used.