The 6V electrical system on these was adequate to light up and run everything when all the components were new back in the day. Also at idle the lights will be dimmer and the signals flash slower. As engine RPM increases they get brighter. The battery provides current at idle but it is not enough for extended operation at idle (or engine not running). After 50 years corrosion and degradation sets in. Corrosion causes resistance, resistance causes a drop in voltage.

The original electromagnetic  turn signal flasher draws a lot of current which causes a voltage drop.

I have a '73 DT3 with a new main wiring harness, tail light cord and turn signal and flasher relay ground wires from DEET, a NOS flasher relay, turn signals, main key switch and left handlebar switch. New MotoBatt MBT6N4 battery. All the frame ground connection points sanded to bare metal. Everything works noticeably better than my 2 original unrestored DT3s.

Also have installed voltage regulators to keep from blowing the headlight bulb.

Gr8uncleal, I wiped the grease, but I left a light coating of it over the contacts. Were you saying it should be cleaned completely?

Thanks for posting your diagram, and it is very readable. I went ahead and assumed that those were supposed to be joined together because they were so close, plus I found that picture in another thread of them soldered together.

Actually after checking it more last night, it IS much better. Before if I had the turn signal on, when I hit the brake, everything dimmed and the brake light would pulse. Now when I have the running lights on and hit the brakes, it basically takes out the turn signals but the brake light is very bright and steady. That's mostly what I was concerned about. Before I started working on it, the brake light wasn't very bright, and if the turn signals were on it pulsed. I was worried drivers behind me wouldn"t notice it. I also understand that when the engine's running above 3000 RPM, it's getting more juice, and I was trying that as I was checking it last night. When I have the running lights on, and turn the turn signals on, the tail light pulses in opposition of the turn signal, but that's not a big deal.

I was thinking about back in the '70s when I rode a CT-1, if this was happening, then it dawned on me that back then I never turned on the running lights during the day, and rarely road at night, so it wasn't something I ever noticed.

So I've basically I've sanded all of the ground points down to bare metal, checked every single connection, and sprayed cleaner in them, and I think I'll get four new turn signal bulbs as well. These are the originals. Last night when I put the new tail light bulb in, it seemed brighter than the old one.