I'm wondering if anyone here has ever successfully repaired a Sheaffer Touchdown filling mechanism? I have a near-mint Touchdown Statesman that I picked up a few months ago at a local junk shop, and everything seems to work fine, except it's not sucking up ink. I've opened it up, removed the sac protector, and checked the sac. It's nice and pliable and springy, so I don't think that needs to be replaced. What else would cause it not to fill?