Echoplex Ep-4 leds all light up all the time

What could be causing this? It's all but impossible to get at the foil side of this board, so I want to narrow it down before I go poking around.

Thanks,

Ben

Fixed it!

Note that the schematic is incorrect: The 1K resistor coming off the cathode of the yellow led cannot be tied to the emitter of Q11 or all leds will light constantly. It can either be tied to ground - this will cause the yellow led to always be lit, and is how my EP-4 came wired. Or I guess you could use the remaining amp section of the LM3900 and hook it up like the other LEDs with an appropriate resistor (40k-ish) from the non-inverting input to 24v. Not sure why they didn't do this at the factory. One guess is that the self noise kept the yellow led lit all the time anyway, so they made it sort of just a pilot light and someone screwed up when they re-drew the schematic... Any insight would be welcome.

Ben