the gearbox on my 2wd cosworth is getting very hard to change gear!
3rd into 4th is difficult but as the box warms up all gears get hard to select
i've changed the oil and replaced it with new millers atf and a tube of stp gearbox treatment! made no difference! is my box needing a rebuild?

 

could be your clutch if gettin hard to change when hot

 

Almost defintely your clutch, dragging most likely.
It could be the cable has done the melting trick, near the turbo and is losing motion here, I had this problem too.
I know on mine I need to fully depress to the very last mm to get a nice change, this was confusing me at first on mine as you can't do the usual lazy change on these cars.
I suspect mine has uprated clutch but don't know for sure as did not put it in, but these are even worse for needing ALL the whole travel.
tabetha