Mk3 Mondeo Gear Selector - Problem in Manual mode.

[LeoMondeo]

I just bought a Mk3 Mondeo TDCi with a 5-speed auto with a selector that looks exactly like the one on the picture below.

 

The gearbox seems excellent and very confortable with good, smooth shifts. However, I have a small problem with the selector. When I put it in manual mode (Drive, then to the side), the selector becomes "loose", without any force to center the selector between the plus and minus signs. I can change gears manually (both with the selector and with the buttons on the steering wheel), but there is no self-centering of the shifter, so that becomes very annoying (and dangerous, because it can just change on its own).

What part of the shifter is used to center it on manual mode? Is it a simple fix? If so, I would like to fix it, if it is not so easy, I could just use the car in auto mode.

 

Thanks again for your help.