You can try an air hammer with a bit which has been ground flat and alternate 'hammering' the end of the shaft and the end of the weight. A fully functional baffle normally has a generous amount of end play, so you won't hurt anything doing this. Once you are able to move the shaft fore and aft, it should create space for penetrating fluid to get in there. You have a combination of rust and carbon buildup which is difficult for penetrating fluid to get in there.
Carl
