Popping out of gear

I have a 2001 Elantra 5sp manual and the mechanics told me that i MAY NEED a new gearbox when i last dropped the car to them when they installed a new clutch. Now all of a sudden the 4th gear decides it wants to pop out of gear whilst driving.

Can anybody tell me what the problem may be ? somebody said something about shift links or rods ???

Apparently a recon gearbox set me back around the $1000 aud mark .... and i dont have that much to spend on fixing up - i'd prefer to put $1000 deposit on another car.

what would the shift links / rods set me back installed ?

ANY HELP FOR A NON-MECHANICALLY MINDED GUY

cheers
brendan

There must be some adjustment on the shifter linkage, I don't know for sure. If so you should find a new mechanic. Installed a new clutch, THEN tells you you need a new trans??? What an a-hole.