That shaft has a very high machining tolerance to the hole it slides into. If you can't move yours then you need to definitly take it out and clean inside the unit further. The shaft should have a perfect gliding feeling with a light coating of diesel, just smooth as silk. To remove the pump further you will need to remove the four bolts on the face then figure out a way to press out the cylindrical center from the squarish outer housing. The center has an "O" ring in grooves at either end and the outer housing has a smooth round bore. During re-install you need to be careful not to shear the "O" rings as the center unit slides into the outer casing. I forget exactly what it looks like inside there (the inner round part) but it sounds like you have gunk in there. You may want to find a pail to put the whole thing in and fill it up with your prefered lube (wd40, PB.....) and let it soak over night. What happens to these is, when they sit for extended periods the diesel creates a shelack (pardon the spelling) coating on the finely machined surfaces and glues the internal pieces together, then when you crank the engine the drive washer breaks so not to destroy the other parts like that quill shaft. Clean, clean, clean that is the mission and will fix your not running problem. The tough part is gettig the center cylindrical body out of the outer housing, it is TIGHT and has to be!