I had the exact same thing happen with an Ultra CDP II safety - they must've been making those ambi safties out of zinc for a while. Wasn't a complete show-stopper though.I had a Kimber CDPII that fell apart in my hands while I was shooting it. Turns out the ambi safety broke in half...
But, even a broken Kimber ran better than that AMT hardballer. Of the ones I've owned, the AMT was in a class by itself.