Crunching into 3rd Gear

[mkc2bad]

Hi

I just had my 2000 2.7 boxster in for a full service inc poly belt change and fuel filter as well as the free whell pulley on the alternator being replaced as it was seized. The car was otherwise in perfect condition when I took it in and the gearbox has always been as sweet as a nut. As soon as I got it back and drove it home, there was a crunching sound when selecting 3rd gear, almost as if I haven't pushed the clutch down far enough. Its much worse if you shift up at higher rpm, but in general the whole gearbox doesn't feel quite as 'tight' as it did before. Now the garage is saying its nothing to do with them and it is now down to the fact that the syncro is worn and would probably be cheaper to just replace the whole gear box. My real question is, could anything have happeend while it was being serviced to suddenly make my gearbox go all crunchy? All the other gears appear to be fine, and the crunch is much worse when downshifiting from 4th - 3rd.

update : I did a little more inspecting and the crunch happens even when the car is stationary and you put it straight into 3rd (every other gear is fine, except it cruched once or twice when selecting 4th aswell) It's then fine on subsequent shifts as long as you don't pull up the clutch (ie keep foot depressed on clutch and you can select all the gears perfectly) As soon as you pull the clutch up (obviously engaging neutral) and then depress the clutch and try and select 3rd again , the crunch happens. Weirdly, it is fine if you select say 4th and then shift into 3rd without releasing the clutch - there is no crunch at all. Is this a sign of a worn syncro? It really does feel like the clutch just isn't fully disengaged.

Cheers
Mike