Known problem. Over time the innards of the switch wear down and it isn't as tight as it was before. It can happen as a factor of time, wear, or a particularly heavy key ring. Basically the switch doesn't "lock" into place teh way it used to, and you have to jiggle it a little (as you've found) to get the various electroics to work.

Not a show-stopper, but you should replace it eventually. I had this problem in my 1985 745t for five years or soemthing before I finally fixed it. What you need to do is replace the ignition switch... it's the silver part in the middle of the ignition column thing.

To do it just pull of the electrical connector (the brown plastic thing with the wires leading into it), it slides forward and off. Then use a screwdriver to undo the two screws that hold teh ignition switch in place. Have the new one in hand when you do this, since you want to make sure you put it on the same way as the old one. Screw it in, reattach the electrical brace, and you are good to go.

The only annoying part of teh job is access to the screws... they screw in towards the driver, so you have to unscrew them blind in a very tight space. You can probably find a good used ignition switch on any junkyard brick. Brand new ones can be pretty pricey.

good luck,
rt