If your stall warning does not “flash”, the flasher unit may be inoperative or a problem with the circuit board.
Send the “Tung-Sol” flasher with the circuit board [singles] to me; I will refurbish and test the stall circuit board and flasher.
That includes disassemble, clean in ultrasonic bath, new properly-marked wires, reassemble, and test. Doing this will at least eliminate that portion from the troubleshooting and assure yours is operative; YT included. One-day turn-around; $60.
The “Tung-Sol” flashers are very expensive new and difficult to find. A later Piper flasher is available but not approved.
I can even provide an mpeg on a disc of the “test” operation but you need to request that or I may forget.