Need a little electrical help with the front yellow turn signals on my 81.

The drivers side blinks rapidly and faintly.  Cleaned connectors in harness,
no improvement.  Accidentally had my electrical pliers touch the 2 hot wires
in the bulb holder at the same time, and bulb began to flash normally.

What gives?  And should these yellow lights come on when I turn the
headlights on? (they don't)

TIA

Adam Puzerewski
81 westy
74 beetle
86 cabrio
Vanagon Partsmobiles