Got A light working, now how about the right back side? BTW i cant seem to get my spark tester to light up for both and it is not broken Old cars are a pain when people have been hacking on them:16suspect
need more info to give you beter advice. you need to follow the power flow. take your test light and see if there is power in bulb socket when the pedal is depressed. also does the running lights work?
do you know that the bulb is good? try switching the bulbs? also if the turn signal switch is on and the key off it turn off the brake light for that side.