Need to check first on the bottom side of the slide for a staple/nail/screw sticking out that is doin' the scratching.
A large pry bar (with proper flooring protection) should easily lift the slide a little, 2" if you're lucky, so you can get a look under there.
You can also look into getting some slide out skis or those slicker plates.
https://www.google.com/search?q=slid...client=gws-wiz