I just took a minute to read this thread. I don't know exactly what the source of the problem is that you guys are experiencing but seen this once before on a reel I have. When I first got the reel it really irritated me but what I realized after a little while was that it had to do with how I was depressing the thumbar. I was used to just barely pushing down thumbar on the outside edge of the bar with my thumb. On this reel that gave me trouble, I found that I needed to push directly down on the bar and slightly toward the spool. Once I started going that, I stopped having the problem. When the reel does get stuck half way in and out of gear, I can get it out of gear immediately by pushing firmly down and toward the spool while reeling forward.

I'm not saying you should have to do that with your reel. Your reel could be unacceptably out of tolerance on the parts that have to do with disengaging the reel, but it's something to try anyway. I attached a lame diagram below :)

http://www.calfishing.com/dc/user_files/4387-thumbar.jpg