What's going on with my center armrest?

[thebigsadler]

I guess I could grab a small video of this in action, but here is a brief description:

Obviously I know that the armrest is supposed to slide back and forth, but it seems that the armrest never "locks" into place so that it can't be slid back and forth with ease. If I 'rest' my arm on it and with any force forward/back, it will slide around. It doesn't take much at all and it is really starting to get annoying because if I go around a turn and my arm is 'rested' it will slide around on me.

I am not sure if I just don't know how to lock the armrest in place, but I have tried nearly everything I can think of.. I would take it into the dealer, but my extended warranty (2000 4.4) doesn't start until Nov 1. I know that the center armrest itself goes for $240 (thanks crevier bmw), but I didn't want to buy it until I posted here and tried a few things. I highly doubt my warranty will cover this?

Thanks for any input..

jason