Dome light problems

[truckin 79]

My dome light in 79 did not work and that has bugged me for a while now. Well I took door jamb switches out and cleaned rust off and used electrical spray, no change. I ordered some door jamb switches but were the wrong size. The thread pattern was to fine but when it contacted metal the courtesy light came on. So I ordered correct door jamb switches and now courtesy light comes on when doors are open but still no dome light. I close the doors and walk away and then the wife noticed the dome light was flickering not fully on just redish across bulb. So am I correct thinking the wiring to dome light originates on drivers side of truck and that is where I should start to look for a short?