Good memory. The crack is more of a chip where it appears the thread likely pulled out like what you are describing. This camera never got abused though. Other than the chip on the bottom, it looks like I went back in time and bought it new from Gundlach, lens and all! I don't think it should be a big problem now that I've had time to take a closer look (I'm at work, so lots of free time, unlike at home!). What I think would be the strongest solution would be to remove the existing hardware, which looks a bit sketchy, and replace it with a T-nut. The chiped area should have no impact on the functionality of the mount, and I would feel better about it in general.
I like the idea of a longer screw. I was thinking of making one that would have a longer reach for my existing head before I found the real problem with the mount, and I may still take your advice and make one anyway. I don't think I could replace my tripod though. It's been all over the world, to the tops of mountains, and just about everywhere I have been. I think it can handle the weight of this camera, at least for now, and I love the three way head. It works fabulously for my 4x5, and besides, I can't afford the Reis. I'll keep a weather eye on ebay for a heavier model for this specific camera just the same.
Thanks for the help!
- Randy