How hard is this to replace?
What might be involved?
Best place to find a GOOD replacement?
It's easy, if you can get the broken piece out of the hole.
But if it's as tight as they usually are, you will have to very carefully drill it out.
The pin that holds the ejector in the frame can be pushed, or driven out from left to right with a 1/16" pin punch.
Try the new ejector in the frame and make sure it fits, and that either leg is not too long and holding it up from fully seating.
A new ejector may or may not have the pin hole in the front leg cut.
If it is not cut, place the ejector in the frame and mark the hole location with your pin punch. Then, with the ejector removed from the frame, carefully file the pin slot in the leg with a round needle file.
Do not try to drill through it through the frame hole as a drill bit will "walk" and wallow out the hole in the frame.
If the old ejector was working properly before it broke, you can match the angles on the new one with it as a pattern. Or better yet, try it and see if it works just as it comes.
I would recommend you get a Wilson Combat or Ed Brown ejector from Brownell's.
The rear ejector leg is only about 1/4-3/8" long - are you sure it broke off?
When I pull the slide off it swivels on the front leg...
Yup, pretty sure it's broke.