[Amps] Arcing noise in Yaesu amp

[José Arturo Molina]

Hi, I have a Yaesu FL-2100B as my standby linear and I just installed it 
because my 30L-1 decided to stay in the transmit mode permanently 
(another repair project for later). The amp uses two 572B tubes.

The Yaesu loads very well but sometimes there is a noise like arcing, 
and I haven't been able to pinpoint the origin. Could it be possible to 
be coming from inside one of the tubes? I haven's seen  any traces of 
arcing when I have opened the amp for cleaning.

If anyone out there has had this same problem, any help will be 
appreciated.

73,

Jose Molina, YS1MS