the allen hole gets filled with decomposed polymer gunk... i've rebuilt a few of these old forks, and have not found a chemical solution to break down that gunk... i've used an extra-long flat blade #1 screwdriver to remove the gunk... i bought that screwdriver from a Snap on truck long ago to tune motorcycle carbs.... note the "judy screw" listed in the Suspension Fork Parts link i posted... that is what you will need to reach/clean/remove.... that fork has been modified to hold the springs, but it looks like you've gotten the spring seat washers out, which is a good thing!
i've seen the polymers turn to sticky goop, and also seen it turn into a clay-like substance... the clay is easier to deal with... the sticky goop is evil and stubborn beyond comprehension. i ruined a perfectly good military bore brush getting that crap out of a Manitou Answer 1 fork. I used a section of a broom handle to extend the 20mm cannon bore brush.

good luck.