I have an Enviro Empress insert with fan issues. The exhaust fan vibrates to the point the stove rattles and drives us nuts and the combustion blower has a knocking sound like a bad engine. Both fans were replaced and the stove was quiet for a few weeks now the noises are back. When the service guy replaced the combustion fan there was a lot of play in the fan blade. ( moving back and forth on the shaft ) which was the issue. Now the new fan is doing the same. Can I take the fan blade off the shaft and add a washer to help or will I destroy the fan. The service guy won't even come back. Thinks we are nuts.