Re: New member, old Gibson.
Welcome to the Cafe, Bazz.
You could do what I did with my '21 A2, which is also has the beefy neck without a truss rod - I made a new bridge. In my part of the world, humidity increases in the spring/summer and decreases in fall/winter, which causes the top to move a bit accordingly. I found it not too difficult, though it does require a good bit of fitting, which is sort of tedious because you have to get it in place under string tension.
I eventually got the new bridge to work correctly, but the whole exercise convinced me that an adjustable bridge would be easier to deal with than a separate bridge for summer and winter, so I put a Cumberland Acoustics adjustable bridge on it.
Re: New member, old Gibson.
I also live where I have a "winter" bridge and a "summer" bridge. I used Red Henry's articles about making fixed height mandolin bridges to make my own. It's fun to try out different woods, too. Walnut and Maple are my favorites for tone on my Mid-Missouri. Here's Red's article: http://www.murphymethod.com/index.cf...&contentId=122