Marking the front pin is a good idea, but you may be the kind of person who wears both a belt AND suspenders. To make certain, clamp both the old and the new ejectors together between smooth, accurate vise jaws with the front pins side by side, and file your groove with a round needle file, giving you a visual gage on position and depth.
Also, don't bother to ask ME how I came to that conclusion. Just look in the bottom drawer of my workbench.
If the ejector IS relieved on the bottom to allow insertion of a screwdriver blade, I would not advise removing it from a stainless steel frame by twisting the blade under a tight one.
[This message has been edited by John Lawson (edited January 01, 2000).]