Clean pan and flint..."gunk" build up won't help.
Uusually about 1/3 of the pan is filled...but the touch hole has to be near the top level of the pan (and as I don't fill the pan, can be a littel below the upper level and i'll not care).
Prefer 4F..it's not that much aster, but every little bit helps.
Vent plugged...paper clip or the quill of a small feather. Doens't seem to make any differnce what.
Will spend the time to clean more often...not so much that you can't keep ahead of the barrel fouling by occasional swabs, but you can't keep ahead of the breech end fouling with damp patches. If anything, just patching the gun proably pushes more gunk down to the breech end (and the vent) that it removes.
SO...if you can stand being non-tradtional...will occasionlly run a patch doen to the breech and then squirt some solvent (even hot water) into the vent...then drag the now dirty patch out and toss it.