Overdrive lever in/out?

[Britcheflee]

I just got off the phone with the old guy who works on these cars - he is confident that its something wrong internally - mentioned shift rail, sprage and that there could also be something wrong with a clutch like mechanism which the pawl engages into - he lost me there - getting the transmission out does not seem to be a huge job and I have help so will do that next week. Will report back with results.