as a auto tech. by trade most tech have a air blower in tool box give him/ her a couple bucks to see if the rod will blow out when blowing in nipple...i would take out nipple for bigger hole to get more air in,....USE CATION WHERE AIMING ROD WHENE PUTTING AIR TO IT,,..,..as a last resort you can remove the plug youerself BUT usally have to heat up with a torch, hopes this helps let us know,,,,,JB