Solution that worked:  I called the IRS e-file help desk (866-255-0654) this morning, 8-1-22 because QB did not automatically put my 10 digit PIN in when I tried to submit, and I couldn't find the correspondence from 2015 when I applied for it.  I had no wait time, was immediately helped by a very nice lady who said that I was her 3rd person asking for this today.  She verified that I had a PIN, and is mailing it to me.  She could not give it to me over the phone, so I am mailing this 941 directly to the IRS.