When it's in rear gear doesnt go notr

Hi all, i just bought a '81 gti and  have a gear problem. There isnt anybody here who can repair this car. For this i need to open this subject here. I searched but cant find, if it was open before sorry. Problem is , when i use rear gear and go , later i cant take it notr position. I force but its impossible to take notr. I stop engine and take off and i use my hand. I pull to left gear rod ( pic isnt mine but same) and take gear 1st. This is stupid but i havent another option. How can i repair this ? Thanks all.

Anybody reply ?

The Mk1 Golf Owners Club

Thanks friend, i 'll try. i hope its work.