Chuck - go ahead and get the 6600P - it's worth every penny. I know, I have had mine for 4+ years. I was able to quilt a queen-size quilt on it, but it was a bit tough on me. I'd really like the HandiQuilter Avante 18 mid-arm set-up for quilting. Since I don't think that's going to happen any time soon, the Janome is a great machine!
As for the needle problem, make sure you have seated the needle in the holder all the way up. The auto-threader won't work if it can't get that little hookey thing into the eye of the needle. I stopped using the threader long time ago. I have a needle threader designed for sergers that I love to use when I need a threader. That is usually right before I figure out it's time for bed!