Following the posts on this thread and what you're experiencing, it sounds very much like the problems I had a few years ago when I had gearchange problems and ended up changing the clutch plate/housing & bearing although I think it was only the housing which was at fault. But as JB says, once you've got in there you might as well do the lot and pack it away for a few more years. (actually I looked it up and it was 2014, how time flies when you've got a Lotus
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I re-read the posts and noted your comment on oils...
So I am assuming my clutch and gear linkage is fine,but the problem is likely in the gearbox or oil choice. The oil I put in was Castrol Transmax manual EP 80w 90
I wouldn't totally discard that one although I don't know how much difference the 90W (hot) grade would make when my manual says 80W. Maybe the higher ciscosity at temperature will make the changes a bit harder, I just don't know.
I do remember way back in the 80s we had a TR7 which I changed the gearbox oil. Of course I didn't read the manual or handbook at the time (how hard can it be ?) so when I came to re-fill it and looked how much I needed I found I didn't have the correct viscosity oil. So I simply put in the same stuff I used on the Elan at the time - it's a gearbox, they're all the same aren't they ?
The first run out the change was horrendous and when I bought the correct oil and saw the difference I could see why. So if the oil change was coincidental with these gearchange problems then maybe that's your only problem, but if you've run successfully with the 80/90 oil in the box then probably not, and it's spanners time again ?
Brian