I used to put some bearing grease on my thumb and press it into the speedo bearing on these old cars . It always cured the problem and never came back. I owned a 1966 Morris 1100 in I think 1990 in the Uk.
A local Mini specialist scoffed at me when I did head work and had hardened seats installed. He told me that he and a few mates did a 5000km WA round trip, buzzing along at 5500rpm non stop. He claimed that there was no visible damage to any component when he tore it down after the trip!
To be fair, 1100 & 1300 FWD A Series engines don't really like to rev too high for too long - they're too long stroke in design... they'll put up with it for a while, then wear very quickly, much more quickly than a short stroke/square
