Have a 2004 K12 automatic. As it's getting on, niggling little problems starting to happen. Just recently the gear shift button has started sticking, it can sometimes take a couple of minutes of jiggling before it will let me shift from Park to Drive or Reverse. This morning it took about 5 mins. Once a gear is selected there's no further problem shifting between Drive, Reverse or Neutral. But it's becoming a bit hit or miss and I'm worried that at some point I'll eventually get stranded with the car stuck in Park. Can't fix it myself, is this a serious (expensive) problem if I take it to a garage? And what is the little black button (you could almost miss it altogether) at the back of the gear selector?