[Amps] sb-220 questions

[Dan Sawyer]

All,

I just picked up an sb-220 and it is not behaving 'properly'. 

It draws about 100 ma of plate current with no input, just the relay 
closed. Is this normal??

It behaves predictably up to about 20 watts of input. It develops about 
20 to 1 gain from 1 watt in to about 20 watts in. At about 20 watts 
input there does not appear to be any additional power out and both 
plate and grid current rise sharply. Is this weak tubes or something else??

Thanks,
Dan