Gear selector not returning to centre

[N8FAN]

My first Porsche, and I'm loving it, however there is a tarnish as the gear selector is not returning to center.
Car is off the road now for winter and I would like to fix this.

I have looked at the selector mechanism and that looks fine. Gave it a clean and lubrication however that did not make much difference.
So then looked at the gear linkage attached to the gear box. The bushes there are rusty and look quite worn and are a bit stiff. The pivot point is also rusty and having popped off the part that attaches to the rod that goes into the gear box the whole mechanism still feels stiff. 

This video below covers it well, though mine is not at stiff as the one seen in the video. 

I am fairly convinced that the issue is the gear linkage shown in this video.
However, before I fork out for a replacement part can someone help me understand what part springs the gear selector back to center.
Is this something inside the gear box itself, the gear linkage or the selector mechanism. 
Am I likely on the right track with the gear linkage seen in the video?