turn signal working intermittedly

Just a couple random thoughts about your issue, if this helps. I have a '68 cuda so not sure if this applies to you. On my car, the park/ turn light and headlight share the same ground which is located on the radiator support just below it's lip, along the routing of the loom. It is a black wire, one on the left and one on the right, attached with a small screw. Unscrew and re-screw to confirm grounding. Thought #2- turn signals go thru the t/s switch. Does wiggling the t/s switch wile in right hand mode make a difference?