Sounds like it needs a cleaning. If you're having trouble removing the bolt handle, the rotating bolt needs to be depressed about 1/2 way for the bolt handle to slide out. I believe there is even a mark on the rotating bolt to show you where it needs to be depressed to? I do it by sense of feel, remove the barrel, slide the bolt forward (gently), depress the rotating bolt head with your right hand and pull on the bolt handle with the left hand. If you've been shooting it for six years and never had it apart, may want/need a pliers to pull on the handle.
Once the handle pops out, bolt assembly will slide right out. Then you need a small drift, or even a straightened paper clip will work, to remove the pin in the back of the bolt assembly. Be careful as you remove this pin to cover/hold the firing pin assembly in place, as the springs will want to shoot the firing pin out the back. Then you can slide out the firing pin and springs. Rotate and remove the rotating bolt pin about 2/3 of the way up the bolt, and remove the rotating bolt head as well. Pay attention to how everything is assembled as you take it out, or even take pics with your phone as you go for future reference since you've never had it apart.
Douse everything with your choice of cleaner and swab out all the accumulated junk, debris, grease, etc. Very lightly oil with a quality lubricant ( not WD-40, rem-oil or other parafin containing oils) and reassemble. There is a schematic for the extrema II than can be found on the brownell's web site as well, if you get stuck at all as to how it gets put back together.
If it's truly been six years, and you've never really cleaned that gun, my money would be on it needs a cleaning finally.
Hope this helps.