Last night I went to Lowe’s. They did not have replacement screw, but we verified that it is an M3. I ordered the assortment from Amazon.
Under close examination with light and magnifier I could see that the threads were stripped. I bought the suggested selection of screws from Amazon. The M3 5mm worked fit perfectly. I applied blue locktight and I think that I am back in business. I have 49 backup screws for the future.PA finally pointed me to Air Venturi for warranty work. Air Venturi has not responded to the email that I sent yesterday.
Under close examination with light and magnifier I could see that the threads were stripped.