Flashers 67 barracuda

You have two separate flasher units.........one for 4 way and one for turn

Find them, try switching them around, or bypass with a piece of wire. Then your 4 way "toggle" should bring on all 4 lamps steady.

Fiddling with the turn sig. switch is giving you results which are irrelevant. The TS switch must be centered for the 4x to work properly.