[Boatanchors] TX4C problem

[Bill and Liz]

I have been playing with a drake TX4C and, after going through the complete alignment process a couple of times, a strange problem persists.  I believe the PA tubes to be weak-power output on 10M is around 50W in CW mode.  But the radio makes 90W on 160M in spite of the fact that there is not enough C in the loading cap and about the same on 80M where the loading cap does peak nicely.  

However, on 40M there appears to be considerably more drive available and power output runs 130W at about 375 ma which I read as being normal.  It is less on 20 and 15-around 90W or so output.  I see only a bit of power sag key down on 10M.

Can anyone suggest why there is so much more drive on 40M?  Is this condition characteristic of the TX4 series?

Bill VE3NH