Hi Mike, I did order the glass plate, may arrive today. I have gone over my gantry carb set up, on the bike, and now off, many times. I traced the sticking to one carb top, one screw and how it interfaces with the gantry. Namely, when I tighten the one inside screw on the right carb, the sticking starts. I can feel it while pulling the short cable slowly. I noticed that the holes for the screws in the gantry don’t align perfectly with the carb top, so when tightened, the screw was pulling the carb top more to the inside. So, I took a small jewelers file and made the hole a bit larger so that it aligns better over the female threads of the carb top. Once assembled, that seemed to help a lot, actually thought I had it licked. However, holding the complete assembly in my hands and flexing the carb, re-introduced sticking. This finding lends credence to those who say all surfaces need to be flat and in a good relationship with the other mounting surfaces. Also, that the carb metal is very flexible, to put it mildly. I don’t see anything wrong with my mounting surfaces, but will check them anyway now that I have it all apart.
I also realized that my sleeved carbs work perfectly without the gantry. One reason is that the Amal carb top is made to hold the slide body round when tightened up via its lip on the underside which inserts itself into the top of the carb body. You lose that when bolting your carb tops up against the gantry so that now there is nothing to keep them round if another force wants to tweak them. I think that is a weakness in the gantry design, and in my case, the less than perfect mounting hole alignment with the carb body. I think if the gantry underside was made to better interface with the carb top, forcing it to keep its roundness, the gantry would be a better product.
If after checking the mounting surfaces and reinstalling the assembly the slide still sticks, I am taking the gantry off. A sticking slide is a dangerous thing to have.