weird popping noise from '73 Silverface champ

[ccrnnr9]

I recently purchased a used Fender Silverface champ and I like it a lot (although not sure if it is exactly what I want). The only weird thing is that within the last couple of days it has developed a small popping noise that starts once the amp is warmed up and the volume varies without touching the volume knob. For example I usually play with the volume at 2-3 and it will make the popping noise and the volume will turn down and slowly turn back up. Any clue what this could be?
~Nick

[Hoodster]

Is your wife opening beers in the next room?

Sorry, couldn't resist. As for your Champ, if it has not been serviced, it is long overdue. A 35 year old amp will need new caps, cap can, tubes, etc.

[ccrnnr9]

First of all I am not married (thank god) so the popping noise is coming from elsewhere. As far as where I wonder why it would all of a sudden start when it has been fine otherwise until now.
~Nick

[Gr8tfulEd]

Couple of basic things obviously:
1. Change out the tubes one at a time and see if that helps. The volume drop makes me think pre-amp tube. I had a tube go bad recently on my Twin Reverb and it had a similar volume issue. It was the first gain stage of the Vibrato channel.
2. Try a different wall jack.
If none of the above help, definitely find a good repair person (good to know this person anyway) and get it serviced.