Since what you described sounded like unbiased transistors and since your bias did not help I agree that would be my next step. As Wilkie says remove the transistors so as not to heat them up and take your iron tip and touch each joint and re-flow the solder. This will insure you have a great solder joint at every location.
I would mark each transistor with some tape so you can put it back in its previously tested space. Then be sure to re-bias again.