I have a 2000 XK. The top starts to go up and then stops about half way up. It then will a little help finish. What would cause it to stop and not finish.

 

Check the fluid level and if low, look for a leak.
If the rams, the leak sometimes shows up as a puddle on the ground at the rear of the doors, but one tht's just getting started is under the rear set in each corner.