Selec-Trac linkage Problem?

Hi. I own a 2000 XJ with the Selec-Trac transfer case. I don't know if I have a linkage problem or not. When I am driving in two wheel drive I have a constant friction sound. (It almost sounds like disc brake pads on the rotor when you spin the wheel but louder). If I push down on the transfer case shifter while driving, it gets worse and if I pull it back slightly it also gets worse. The four wheel drive does not shift in and out very well either. Last night I could not get my 4fulltime to engage. On dry pavement when I took a turn it was always locked in. The part time will only engage if I pull it back to fulltime. If I push it back to part time it will stay in parttime. What are your opinions? Should I have the dealer look at it and what do you think that constant friction sound could be? The friction sound seems worse at low speeds and when I'm on the gas.