Rosco,
I didn't keep my BX long enough to solve that problem, but I definetly had it. And my grease zirk worked fine. I greased the daylights out of it.
My theory is that there is more than one cause for this problem, since different people have done different things to solve it, while others have done everything and it still sticks.
I noticed on mine that as long as the tractor was not running, the pedal would snap right back. It was only while the engine was running that it would be slow to return. That told me that my problem was probably inside the bowels of the beast, and not likely to be the (external) linkage. You may want to do this test on yours.
Good luck.
KB