I will try to pursuade it to come out with a block of wood.
Success! It took some beating, but it came out enough that I could get a grip on it with pliers and tug it out. There was a small burr raised on the front edge of the notch for the retaining pin and that was dragging in the bore and preventing the ejector from moving forward. The spring was fairly munched, probably from my pushing the ejector in while trying to get it to pop back out. I pulled it back to where it looks approximately OK and stoned off the burr, but I will be replacing both pieces with new parts.
The rifle now ejects properly, albeit pretty weakly with the mangled spring and ejector. Thanks to all for the help.
Mark