Many thanks for all your help. I ordered a blade adapter from EB. I cleaned the blade bolt and added a dab of red thread locker. I also added a large flat washer and a new split washer under the bolt. A final torque (guessed at number ‘cause I couldn’t find it anywhere) and no loud noise after a 15 min. run. Thanks again for your help.I’m guessing your problem is caused by a combination of the use of never seize and a bad blade adapter. I personally never use it and never recommend it, but others on this forum call me a crazy old fart.