I have inserted the upperpart of a hard plastic bottle with the right curvature in the gear change turret of my MG PA around 1980 to cure a similar problem.
Still going strong today with very smooth gearganges !
Hi Maurice The forum topic discussing the repair I made to my turret gear lever ball joint in the following forum link. http://www.triple-mregister.org/forums/topic.asp?TOPIC_ID=12042&SearchTerms=gearbox,turret Made in duralumin, working 'like new'. To make exactly, recommend make in situ with the remote, gearlever, and turret. I could make one, if supply gear lever and turret. I can use my remote (very experienced at removing it now!). Made to exact push fit, so if ever needs to be replaced again, can be pushed out. Lubrication using petroleum jelly. Donald PB0759