That's the way any replacement screw needs to be modified. Look at the original screw and make the replacement look just like it. That one was custom made for that application, apparently. I usually lathe turn a hex head bolt to fit there and hacksaw a screwdriver slot into it.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!