Wow, it's been quite a while since I have heard anyone speak of the infamous Grendel. Don't chunk it, but don't count your life on it either. It can still be a fun range gun.
I second the other poster's response about contacting Kel-Tec. They may have you send it in or they might send you something to fix your pistol, who knows. But they have EXCELLENT customer service, probably better than 99% of gun makers out there. They will make it right.
Stinger