I had a similar problem. The safety was very difficult to engage and sometimes the lever would not turn at all. I assumed there was a burr in the bolt somewhere. I took the bolt out and the safety was a little easier to engage. I put on gloves and worked it back and forth. That got painful after a while so I continued with pliers - probably 200 times. I put polyethylene tubing on the plier jaws to protect the lever and bolt. I fired another 20 rounds and now the safety works fine.
