[Amps] Pop (arc) noise in Alpha 99

[Ken, KA0W]

Hello,

Comments on the Alpha 99 being susceptible to dust, fuzz, etc. 
getting into amp and occasionally producing a pop or arc noise? Had 
an old Clipperton-L that occasionally popped off from airborne 
particles and pests. Wondering if others have this problem with the 
Alpha 99? Occurs at random, even in standby. Just wondering (a little 
concerned), does not appear to affect the 99's performance.

Thank you for any comments,

Ken, KA0W