Tim,
I bought a very early GAHH top about 3 years ago and eventually experienced their problem with the glass separating from the top. That top was replaced with a new one. During these top changes I experienced a couple of problems and can give you some possible causes.
First, my top is still harder to latch when compared to my original top. I think it has loosened over time, but it still takes more effort to latch and probably always will. I choose to leave it as is because it works well and isn't that big of a deal for me.
The other problem I experienced is the top edges on both sides wouldn't always go in the grooves along the tops of the windows when closing. I had several broken parts that were replaced when my second top was installed. I think they were broken during the install of my first top. Here are some pictures of the broken parts:
There is supposed to be a pin in the hole that allows this part to rotate properly when the top is lowered/raised. The pin wouldn't stay in position because some plastic tabs were broken on the other side of the hole.
This is the other side with the pin in place.
This piece has some broken tabs on the vertical part.
I think the broken pieces on my original GAHH top caused these straps to be stressed and to break.
My second GAHH was installed by another shop that found and replaced the broken parts. The top now works very well. GAHH was great and covered all costs. Despite these issues I love the top and am glad I went with it.
I'm not familiar with the Robbins top and of course don't know exactly what is causing your problems. These are just a few things to look for that may helpful to you or someone searching in the future.
Peter Serbanica installs tops and will hopefully chime in with more insight.
Best of luck,
ddb