I have a Yugo SKS that fails to function. I have: totally disassembled it and scrubbed thoroughly with Simple Green replaced the gas valve with a new one from Gunparts Corp replaced the two gas pistons with new ones from Tapco. I best I'll get a stove pipe and at worst the gun will fire and the bolt will not cycle. And yes, the selector is off the grenade position and onto the semi auto mode. Any solutions before I put the thing in the back of my gun safe-way in the back?