[Central-Electronics] 600L Problem Diagnosis

[Barry Graves]

New member here.  I'm a CE fan and have a couple of 20As, 10Bs, slicers, MM, and most recently a 200V and 600L.  
Recently a problem cropped up with the 600L on 80M band.  The amp has low output and more alarming, the grid current pegs on key up and the reflected power deflects the meter to the left (both conditions on the 600L meter).  A quick test on 40M was perfectly normal so this seems to be limited to 80M and not a meter problem.  I'm hoping this is not an output coupler problem.  Looking for advice on what to check.  Is there a test method and expected measurement guide for the broadband output couplers for example?Cheers,BarryKJ5GQM