my 52 plate wrx impreza crunches into fourth gear from third, it only happens when the engine revs are over 4000rpm-ish, the rest of the gears are fine.

if it is the syncrmesh how many £s are we talking to fix the problem

the car has done 62000miles with full service history

cheers

i have the same problem on mine at the mo....call david at "api" as he is gonna be sorting mine out soon.
Probably synchros like you say...could cost anything from 500 -1000 depending on what it needs and whether you take the car in and let him remove the gearbox for you.

have you had a fluids service recently? If so the gearbox oil might not be the right spec.. I've had this a couple of times on mine and changing the oil to a different type fixed it.. maybe that's a cheaper solution. However it's best checked by someone who knows first...