Gear selector cables

[fourtwofive]

Right need some advice basicaly I find it hard to find third gear it grinds at high speed I have adjusted the select cables and third gear was fixed but then you can't find fourth.
Is it possible that my gear cables have stretched and also if you reset it gets a lot worse ...

 

[Seatmann]

Might be to much play where the selecter is on top of the gearbox, where the reverse light switch goes in.

 

[fourtwofive]

I'll have a look it's going back to the gearbox specialist asap doing my head it grinding third all the time