I have purchased a new carb already. 5.5 hp B&S. I think I damaged my old carb by using air pressure to clean out the old gas. The rubber seat under the needle came out and there is no way to get back in. Can this be repaired?

Your talking about fixing the old even though you bought new, right? You can buy a carb rebuilding kit for the old carb. Never used compressed air to clean a carb, spray carb cleaner should be the strongest stuff you use.

Typically compresed air is used to remove the rubber seat, as ballenger stated a new kit can be purchased and it will come with a new seat. Use a allen key the same size and gently push it in.
Don