^^^^^ New? over a single cover screw? That's like trading in the Rolls when the ashtray is full.
And is there such a thing as a _new_ Shimano 7-speed shifter? (Probably 7-speed, being a '97.) NOS, maybe, but that usually means NOT cheap.
Since it's a cover screw, matching up a new one based on the one from the rear shifter is a pretty safe bet. There's probably one in a coffee can or mustard jar at a nearby bike co-op (depending on the OP's location).
AllWeatherJeff - can you elaborate on "will not shift into the large chain ring"? What _does_ happen? Looks like this is a trigger (not thumb) shifter. So when you hit the "bigger ring" trigger, what happens? Does the trigger fail to move far enough to move the derailleur? Does the trigger move, but fail to engage anything in the shifter? Does it move, engage, move the derailleur, but fail to "keep" it on the large chainring? Or something else entirely? Knowing what it _does_ (rather than what it doesn't do) will help troubleshoot.