Brownells has a kit with the ejector pin, ejector clip, two springs, couple other parts – but no stock and $60.  That's pretty expensive for that little spring I need!  I can make one – I think the photo in the Brownells catalog shows the spring well enough.  It's not really that precision – just has to kick out the brass – diameter smaller than the pin, long enough to push on the ejector pin, short enough to let the pin retract fully.  Just wish I hadn't lost the original.  Had disassembled and put all the parts in a plastic bin on the bench – went to reassemble and the spring was gone.  I think I have a spring gremlin living under my bench, as this isn't the first spring that has disappeared from this bench! – UPDATE – crawled around on the floor ONE MORE TIME before I headed to the shop to make one and FOUND IT!