Solution to pop off issues and receiver not pulling close enough to base: first make sure liner is not too tight. I had to increase to a 2.5 from 2.38. First insert erect penis into lubricated receiver without large hose connected. Next, turn unit on and run slowly – at the pace of air in and out every second. Last: with erect penis in proper fitting receiver and machine running as stated… Push receiver to base of penis- then hold large hose “near” receiver port (slightly touching). You will feel the air either push receiver off or pull it on. When it is about to pull on…. Connect large hose completely. You now have lots of suction and should be stroking very close to base. Now all you have to do is add air to lengthen stroke if you want. Works super fast and holds completely! Air out button will work the same but you may have to press it lots (I mean lots) to match the speed and effectiveness at which the above method works. Theory: erect penis inserted into the closed system increases internal system pressure which needs to be released. Hence, method above!!!