At least I am not alone on this problem. However, I don't have to worry about it for another year since I haven't gotten to the point of putting the inner skins back on.
But yes you are probably going to have to disassemble the hand pump and replace the O-rings and perhaps any gaskets as well. Unless you find something solid is broken inside the pump, a quick trip to the hardware store should help you fix any O-ring issues.
"Some things you can tap. Some things you can hit. Know which one is which!"
1948 Airstream Liner 22'