I found my problem, or at least I'm pretty sure I found the problem.
I had put a metal rotor head assembly on the heli, and right after that was when it started acting weird. After all the frustration, dinking with the transmitter, fiddling with the links, I noticed that the swash plate wouldn't go up and down, and that the servos seemed to be binding somehow. I could disconnect all the links, and the servos worked like a charm, but when I connected everything up it was all locked up again.
I was completely bumfuzzled, so I took all the connectors loose and then reconnected them one by one, each time checking the servos. They seemed to work fine until I hooked up the oval connectors between the swash plate and the flybar link. That's when everything would seize up.
And then it hit me - when I had installed the metal rotor head, the flybar connector holder had been very tight on the shaft. Dummy grasshopper here thought that it was SUPPOSED to be tight to hold everything on. DUH!!!

After a good bit of twisting, cussing, and breaking the guide pins off the T-holder [:@] I got the flybar connector holder off. I drilled the hole out just large enough to slip over the shaft, and now it works as it should.
Of course, now I need to make another parts order, so I'm going whole hog. New T-holder, new blades, new landing struts (one got broke early on) new connectors. I think that now I'll have a heli that will fly right as long as I do!!