[Collins] Exploding 6146 in KWM-2

[Dave, K2DP]

Food for thought, anyone have some ideas on why a 6146 would literally explode in my KWM-2 while the rig sits in the receive mode ? That is, other than the fact than the tube date code is "63-30" meaning that it is 43 years old !!!!!! Frankly, at that age, I'm not sure what any tube will do, but I am curious to know if others have experienced a similar type failure. Visual examination of the PA circuit in the KWM-2 and the 516F-2 do not show any visible HV capacitor or high wattage resistor failures. 

73 and keep'em glowing !
Dave, K2DP,. St. Louis