Thanks for the tip George. First, I'll try the 5555. I probably tried that, among many others, but I was focused on getting the 1555 to work.
Second, I'm trying to get in touch with the previous owner to see if he installed this himself and reset the installer code. It would be like him to have installed it, and if he did, he would have used a new installer code for security as well.
Third... you're prescribed testing to see whether it is locked.
Thanks...it's nice to have the advice of a genius...!!!