UKPassats

Only recently I have had problems in getting into 3rd and 5th gear I have to take it out and put it back into gear or force it. I drive not hard at all and only gently flick the gearstick into gear so do you think it's gearbox needs an oil change or the linkage playing up?? Only does it sometimes when engine is hot or cold it's sort of random anyone else had this.
1.9 b6 bxe engine on 170,000 miles