Regarding poor gain, I fixed a friends QCX and the problem was two resistors swapped, a 1K and a 10K that made the gain very poor. I think -90dBm was the weakest I could hear with the fault, and around -125dBm with the resistors in the correct locations. IIRC it was R34 and either R25 or R26. You should be able to measure the signal at each stage and see that it has the proper amplification as well, if you have a scope at hand.
Daniel Ekman SA2KNG