So, one of my last electrical issues I am tracking down on my car (78 280Z), is the park lights.

 

They DO work, but they work selectively; I can turn the headlight switch on one turn to activate the parking lights, and the interior/park lights may not activate. However, with some gentle tapping of the headlight stalk when they are in the on position or some moving of the entire switch (rotating the entire turn signal and headlight switch on the steering column) this will also result in bringing the park lights on.  Headlights work always with no issues.

 

The most likely culprits that come to mind are a corroded rocker in the switch or a nub that pushes on the rocker is wearing out.

Rockers and nubs, note the burnt/worn nub at the top right that needs replacing. Buildup on the rockers that needs to be polished out.