I've got an old Rossi/Interarms .38. I lost the "thumbpiece screw" at the range. I've had this pistol forever, and I really like it. Any help on where to buy parts? Will parts from another gun (S & W) fit? P.S. I've already tried Numrich. I think I'll go with the Pachmayer grips from a previous post, but I still need to find the screw...Any help is appreciated......