1968 GMC Front Turn Signal Issues

[68gmcdude]

Hi All...

I'm having an issue with my left front parking light/turn signal. So far I've checked the bulb and cleaned up the ground. Here's what's happening.

With key off and only the parking lights on: Light does not work.
With key off and parking lights/headlights on: Light does not work.
With key on and all lights off: Turn signal works at normal speed but is half as bright.
With key on and only the parking lights on: Turn signal drops to half speed and is still half as bright.
With key on and parking lights/headlights on: Turn signal is still half speed and half as bright.

I am not good at electrical issues so any help and guidance is greatly appreciated.

I have have new wiring harnesses coming for the rear lights because the reverse lights keep blowing fuses and I can't figure out why. I'm assuming the rear lights won't effect the front lights, but maybe they do (?),

Again, thanks for your help!