I'd like to remove these two American Standard shower handles, particularly the one with the starbust design, so I can clean out or replace the cartridge.

I'm having trouble removing the set screw. It looks like it takes a slotted screwdriver, but I tried several, and they don't feel like they're engaging the screw at all. Anyone know what size screwdriver or allen key I should be using?

Also, if you happen to know the name of this trim style and the model of cartridge, it would be helpful. Though I do have a great plumbing supply store that can identify the old cartridge if I bring it in.

Thanks!

Name:  upstairsShowerHandleSmall.JPG
Views: 3288
Size:  11.5 KBName:  downstairsShowerHandleSmall.JPG
Views: 3112
Size:  15.1 KB