frankpl on here has Removed one or a few by drilling a few small holes around the cap, then w/ the HELP of a couple of Friends push the inside ring towards the glass & remove spout.
2nd page of Patent Drawing [below] shows the Oil Dispenser spout for filling the Fil-Pruf bottles.http://www.google.com/patents?id=415oAAA...TEM&f=false
I turn upside down & insert tube from WD-40 thru the flappers, then turn back over & squirt WD-40.
Just pour paint thinner in top, let sit for awhile to loosen sludge in bottom, shake vigorously, pour out. Then use soap & water to remove the WD-40/paint thinner.