[Amps] TL-922A - Loud Pop, Blown Fuses

[Clay Curtiss W7CE]

Yesterday morning when I turned on my TL-922A, there was a very loud pop
followed by blown fuses.  I replaced the fuses, changed the setting to CW to
reduce the B+ voltage and tried again.  Similar result with several smaller
pops and then blown fuses.  I use a footswitch for T/R control and it wasn't
depressed nor was I transmitting with the exciter when I powered up.  I
should also mention that I've heard a pop on power up two times previously,
but neither time caused a blown fuse.  I opened it up today for a visual
inspection and see no signs of arcing or anything unusual.

Before I dig into this thing, has anyone else experienced this problem?  Any
hints or suggestions to reduce the troubleshooting time will be appreciated.

Thanks and 73,
Clay  W7CE