I am trying to get a pair of Drake twins on the air. The receiver is an R-4 I have restored and it works perfectly. The most recent attempt at joining a Xmtr is a T-4XC. Everything works in the Tune, CW and AM modes. Spot works. Problem is with SSB. Max output with a whistle is about 4 watts. On a separate receiver the audio sounds OK, just low (very low) output in that mode. Same mic on AM so that's not the problem. Have cleaned the tranceive and mode switch wafers with no improvement. Same result using either VFO or separate. Any ides?