GPG wrote:
I have an electric cylinder mower of about 1982 vintage.

It has pretty well stopped working because the motor brushes have worn out.
Fiddling with the brushes, I can get it to go for a very short time.

I have no idea where to get suitable replacements. Do they come in standard
sizes, so that I could measure them up and get a pair from somewhere?

It is unlikely to be of much help if I mention that it is a Qualcast
Concorde RE35 S, I guess

If you go to someone who services lawnmowers, they might be
able to tell you what to get, or get them for you. If you
can't get the right ones (which would be quite surprising)
you could cut down larger ones, they're quite soft.