Gear stick laterally stiff
 

I have an 04 Boxster with 31K miles and a 5 speed box. The gear lever has become stiff to move from side to side and no longer centres itself betwee 3 and 4, making changing down from 5th more difficult. All the gears engage and work fine. Cable end linkages have been lubricated front and rear but no real improvement. Anyone had a similar problem?

When you push the shifter side to side it rotates inside white nylon plastic bushings and plastic inserts; one in front and behind the lever. My guess is you have binding in there preventing the shifter centering. You can't pull it apart easily without breaking the bushings, so it might be a good time to upgrade to an aftermarket unit or maybe a 987 5 speed shifter.

Have you by chance put any coins in your ash tray? The can get into the shifter mechanism during spirited driving.

You can always pop off the leather trim around the base and have a look to see what's going on, spare change or not.