I have a "Thinner" scale, too, but it doesn't sound like yours. They have a bunch of different models. I don't think there's a way to adjust this one. I bought it on line from www.msiusa.com
and so did a friend of mine. I'm thinking it's the company that makes them...anyway, mine's perfect--always right on, no matter how many times I get off and on it. My friend's got little kids, so her's got tossed around some--she called the company and they sent her a new one! (Dang, I thinks she's done that twice.) Might be worth a call. Good luck!

Patty