Green Pre gain not working

[bluezplaya]

I've got 4 Green pre's in a case that all work, except the gain (Lorlin switch) on channel 3 doesn't affect the signal. The output volume pot works but the signal is about a third of the other channels when it's up all the way. I checked voltages across all 4 boards and they seem to be pretty consistent. The 5532s are getting 15v+/-. Could it be one of the two BC550s have gone bad?

Any advice?
Adam