Update. Recall that the Dim bulb stayed dim with everything hooked up to the Control Board except B+ and B- on 12L and 11L. When I connect those rail leads, the dim bulb burns bright.
Today, I left the B+ and B- connected and pulled all the other wires off the bottom of the control board (Q6 transistors still hooked up). Power applied, Dim bulb stayed dim. As I reconnected each wire, the dim bulb stayed dim until I came to 3L (Q12 Base), so I left it unconnected and continued left-to-right. The dim bulb again went bright when 9R (Q11 Base) was connected, so I left it unconnected and continued until all wires were back in there respective spots.
So with either 3L or 9R connected, I get the dreaded bright bulb. Looking at the schematic of the Control Board these connections lead to Q9L and Q6R, I checked and they are the appropriate devices, MJE15035 and MJE15034, respectively. With full AC voltage applied, the measured voltage on 3L was +14.2V and the measured voltage on 9R was -.22V on my digital Fluke. The voltage on 3L seems high...
Just for fun, I measured the disconnected Q12 Base wire (goes to Control Board 3L) and measured -82V (rail), while the other disconnected Q11 Base wire (goes to Control Board 9R) measured -.15V. This seems correct with no inputs connected.