Nah, I have to disagree - a clogged valve usually kills all floors, not just one fixture.

Is your shoulder alright or did that thing leave a nice bruise to remember the job by? Because honestly, a fist sized chunk of creosote to the noggin sounds like the universe telling you to take a longer lunch break. Extra 45 minutes of cleaning from the bottom sounds like a nightmare, but hey, at least it didn't land on your ladder or knock your bucket off the roof. I guess that's the old house's way of keeping you humble, right?

Tried the same thing with a yellowed Game Boy shell and a $3 bottle of generic 40 volume from Walmart. Worked just as good as the kits I used before, maybe even better.