Thanks Ian.
Your feedback was the encouragement I needed!

I was able to light the bulb but it remained on when the stalk was in the middle, left or right positions.

If I am reading the wiring diagram correctly it appears I need the flasher unit.
So... I will temporarily install the steering column and connect to the wiring harness.
If I attach the battery + terminal to the input side of the fuse box (white wires) and ground the - terminal I should be able to test.

Does this sound correct?

Attached is the wire diagram.

25 = flasher         LGP=green light    LGN=turn signal
26 = turn signals  GW=right  GR=left
27 = green light    LGP

Hi Roger, just find the wire that powers the indicators, clip the bench battery power to it and the earth to the metal bit that bolts to the steering column.  Hold the mount in your hand and push the lever up and down.

If you put a multimeter on each side of the indicator output you should see 12(ish) volts on your meter and the green light should illuminate. (Wont flash of course because you don't have the flasher can in the circuit ...... although this should be rigable (if that's a word)).

Cheers, Ian

1966 Austin Cooper S

I just used my bench battery to test the small light bulb.  It works so I screwed it into the socket at
the end of the stalk and replaced the green lens.

I have the steering wheel out of the car sitting on my bench.

Is it possible to test to see if I can light the bulb when I move the turn signal to the left/right position?
If yes, how.

if no, what other options might I have?