Newbie from north of 49

Just got the plates and doing some pre-drive stuff. I like to do the oil, plugs and fluids change thing just so I know it's current. Got the Amsoil oil with zinc so should be good to go. Did just notice that my left taillight and signal isn't consistently working. Seems about a few or 3 decades ago my 69 Swinger did the same thing. Just can't remember what it was, thinking it was the turn signal switch wiring or something. Gave the wires on the column a little shake now it's consistently not working...LOl Any ideas from you guys on possible things to look at?