I have a renault espace 1988 petrol, i seem to be have problems putting it into gear, ?

im having to pull off in second gear at the moment, i have had the linkage done not so long ago by a friend of a friend, the high gears are ok when im driving, but when i have to use low gears " first or second" its stiff going into it, so i don't want to force the gears in to it, ive been told maybe it the clutch cable loose, the gears work good when the engine is off, so i know it not the gear box or the linkage, any ideas any one thanks Doug