Originally Posted by bulgie

Important: check your seat tube for a cork, and remove it if it's there. With the seatpost and bottom bracket out, put a flashlight in the BB shell and make sure you can see it down the seat tube from the seatlug end. PX-10s of that era often had a factory-installed cork, and some of those frames completely rusted out from the puddle of water that collects on top of the cork.