Nothing is quite as annoring as a saggy lift gate. I've had to deal with it since I got the top in 2003. So here's a visual guide on how to replace the struts. They're cheap too. I think the two I got were under $30.
This is as far as the lift gate goes. Well, it goes up further then drops.
If your top had rear defrosters you'll want to make sure to get the struts with the wiring tabs. To remove the struts place a screwdriver into the slot under the metal band.
It doesn't take much to release the strut from the ball socket.
Just be careful when installing the new struts. They are very strong and can get away from you.