My front water dam was completely rusted off the rest of the hard top. I actually had to cut the water dam off to remove the top. The hole allowed water to get into the cab and destroy the bolts that hold the hard top to the windshield. A good fiberglass person should be able to restore the problem areas.
The hard top is actually pretty easy to remove if your nuts and bolts are in descent shape. There are lots of bolts to remove so if you try to lift the top and it doesn't move easily, then look around and you will probably find something else to remove. I actually removed the hard top by myself. I lifted the hard top off the body just enough to slip 2x4's between the top and the bed rails. Then I attached lifting slings to the 2x4's. The lifting slings were attached to an engine hoist and Voila! the top popped right off. Make sure and strap the top down to the 2x4's securely in case you get it off balance. You don't want to drop it on the ground.