Okay I replaced the tail lights (2057's) and front flashers (1057's) (along with the front and rear marker bulbs (194's)... I hit all the sockets with CRC and some rags. The front flashers sockets seem to be packed with some sort of insulating grease (zinc paste?) mustard yellow stuff with the consistency of peanut butter. I ended up fixing the SLOW flasher but they are both still slow just not as slow (comparing with my Boss' identical YJ). Irritatingly slow but better than the 2 second interval the right flasher was doing before I cleaned and replaced them.
Question: does the zinc coated metal plate inside the tail light housing play a part in the grounding process? The mounting bolts (if they are part of the ground) are rusty and could be the source of the slowness.
Question 2: is this zinc paste stock or something that somebody packed in there to reduce corrosion, but that may be adding resistance and thus causing the slow flash?