[TenTec] Low output on Centruion after lightning

[Jim Miller WB5OXQ]

I have a Centurion about 6 years old that has always made around 1200-1300 watts on all hf bands except about 1000 on 10 meters.  I recently had a lightning strike to my fiberglass dual band vhf uhf antenna on a different tower from my hf antennas and neither of my hf transceivers were damaged.  I now find that I can only get about 700 watts on any band driving the amp with either transceiver.  Could this have damaged the tubes?  I don't mind a new pair of 3-500's if that will fix the problem.  Should I buy the regular 3-500z tubes or the zg graphite models.  Will I gain anything by using the graphite plate tubes?  Any mods anyone can recommend that will improve the amp performance while I am in there?  Suggestions please!

      Jim & Ella Miller 
WB5OXQ & KA5EPM
     Abby & Sparky
Dalmatian Furbabies
        Waco, TX