Hi John,
I can appreciate you situation.
To start, I have attached a picture of the Directional Indicator circuitry I created in order to understand the operation of the Flash Relay Box and the, especially convoluted, operation of the dash indicators. Many years back I had converted my BJ8 Phase 1 to negative ground, however, the general diagram holds true for most Positive or Negative ground Pre-BJ8 Phase 2 Healeys and the operation of the dash indicators for all BJ8s.
In short, one filament of the the 1157 double filament bulb is used for Running Lights (RL) and the other for Signals Lights (in the rear, Brake (BL)or Directional Lights (DL)). When the brakes are applied and the Trafficator set to activate the directionals, it is the Flasher Relay Box that determines whether the signal sent to each bulb is constant on (Brake), or Flashing (Directional).
In your first recent post, you indicated that, with the lights on, your front running light was illuminated. Were all other running lights illuminated as well? When setting the directional to left, was the key on? Did you mean the left RL went dark at when activating the left DL?
As indicated in your second recent post, clean contacts are important and inactivity will promote insulating corrosion faster. Have you verified that filaments of the left front 1157 bulb are working. Also, if the bulb proves good, have you cleaned bulb and FRB contacts, including ground, before applying power to FRB terminal 2 to see if the front left signal filament lights up?
Although we will finish up with the dash indicators, here is a preliminary explanation of their operation. Once the Trafficatior is activated, power is directed to terminal 4 of the FRB and also gated from the flasher to power flashing signal lights. Power is also directed from the flasher to Both dash indicators with only 1 grounded through terminal 6 on a left turn and 2 on a right turn. Since, on a left turn, power is being directed through terminal 2, the right dash indicator has two power lines and no ground. However, the left dash indicator is being grounded through the fight bulb to a ground. Yes, this is convoluted and I changed my setup to be as previous models by adding a ground to each dash bulb and switching power lines on the bulbs.
Good luck and stay safe,
Ray(64BJ8P1)