ive got an sa 200 about 82 model i think  when i got it the shunts were out  i replaced them and it welds ok now ive been running it for about 3yrs now  im trying to get it dialed in because im trying to break out  the problem i have is that the polarity field seems to be reversed  bu that i mean that my ground strip going to the negative lug is positively charged and the cable coming out of the armature is negative  ive heard that there is a way to fix this does anyone know the process?  any help would really be appreciated thanks