Triumph Repair: GT6 Turn Signals, turn signals, fuse box

Question
I've recently spent quite a bit of quality time with the rear light assemblies on my '73 GT6, trying to fix what turned out to be a faulty connection at the fuse box. Now the brake and taillights work (finally), but the rear turn signals won't (The signals are on a different circuit from the faulty one, and I went ahead and cleaned all the contacts for fuses). The front turn signals and the turn signal warning light will come on, but there's evidently not enough current passing through the flasher relay, since they'll stay on without blinking. Hooking up my 12V test lamp to the wire feeding current to the rear turn signals will intermittently show that the wire is live, though I can't seem to find a reliable ground for the test lamp in the rear of the car, so that might explain why it will only sometimes show current. Additionally, the lights will intermittently work, though it's nothing I've done when they do come on. Once though, the driver's side signal began to work reliably, and, on further inspection, I'd mounted the bulb holder incorrectly, so that some of the metal splines that should go inside the light assembly to secure the bulb and holder there were on the outside. A grounding problem perhaps?
At any rate, I'm at a loss. I've thoroughly cleaned the contacts in the bulb holder, and have even swapped the bulb holders between the reverse lights and the turn signals, after which the reverse lamps continued to work, but there was no change in the signals. The only thing I can figure is that the connections on the hazard switch are worn or dirty, but it's quite difficult to get at those connections, and the fact that the front signals work, but would seem to rule out that possibility (The hazard blinker functions only intermittently, if that helps diagnose this).
Any insight into the problem, or perhaps tips for cleaning the fuse contacts behind the box more thoroughly? I can't seem to get at them, and they might still be the issue. This is the last electrical issue plaguing the car, and I'd really like to get it fixed.

Thanks

Chris

Answer
Hi Chris,
I can't tell you where your problem is but I can tell you how to find it. I always start at the load (item that don't work) In your case both rear turn signal lights.

First just turn the the turn signals on and take the rear bulb out and with a test light check the pin connection in the socket for power. If it does not have power just take your wiring diagram and start at the rear of the lamp assembly at the plug connector and test there for power and continue on toward the source of the power. (turn signal switch) If the fronts are on then the turn signal switch is working and it has to be a problem at the socket of the wiring.

To test the ground all you need to do is run a long power wire to the back of the car and attach it to the clip of your test light and start by probing the socket wall and if it lights then the ground is ok, if it don't light you need to check the back side of the light assembly to see if it uses a black ground wire or just the mounting nuts to the body but you can use the test light to locate the loss of the ground no matter where it is.

If you don't have a wiring diagram let me know and I will put one up on my web site for you to copy.

Howard