annoying gearbox on a mrk 3 golf se 1.4 ?

hi i have a mrk 3 vw golf 1.4 se its needing work done to it one of the annoying problems with it is that when you some times put the car in to reverse, 1st or 2nd it seems to be a battle with the gear lever 3rd, 4th and 5th are no problem could it be something simple outside of the gearbox like a gear selector plate like on mrk 1 fiestas or am i fearing the worst and needing a new gearbox all together