[Amps] Excessive Plate Current

[Tim Long]

Hello All,
I am a newbie amp owner and have a Clipperton L. It has a Dahl 
replacement transformer that provides about 2625 volts under load.  It 
appears that the tank circuit is original but that's nearly impossible 
to determine.  I have two sets of 572b's.  When driven with 100 watts 
and tuned for maximum power into a 50 ohm load, 80/40/20...
Set #1 - 4 Raytheon's
plate current is around 850 ma, output is around 400 watts
Set #2 - 2 Certron's and 2 GE's
plate current is around 500 ma, output is around 300 watts
The loading control is at minimum (max cap) or very close.
What am I looking at and where do I go from here?
Thanks in advance & 73, Tim, W2UI