Lonestar problem

[Pegleg]

Hi Guys.
I recently bought a used Lonestar Classic 1x 12" combo. circa 2005. I've noiced that when it's been running for a while the level drops and output becomes fizzy/ breaks up. It does it on both channels it seems. It seems to clear sometimes if I switch the standby on and off. I suspect this is a valve problem, and if you agree can someone tell me which valve it is likely to be ?. (not electronically minded at all) I have checked that they are all firmly seated, but I don't fancy sticking my hand in to tap the ones set furthest in to the chassis with it switched on lol. I suspect these are all the original valves so maybe time for a complete change anyway (any recommendations ?) , but for now I just need to sort out this issue. Thanks for looking.
Kev

 

[Barry]

Try replacing the preamp tubes one at a time with a tube you know is a good one .

 

[fishyfishfish]

My '05 LSC was doing the same thing, and it turned out to be one of the power tubes. With your amp on a table and good lighting, (and dry hands with no rings or watches!) you can gently tap on the metal pre-amp tube protectors with no problem at all. If this still makes you uncomfortable, use a chop stick. There should be a slight "Knocking" sound, and thats it.
The power tubes should be quiet when tapped on, and with an '05, I would say it's time for new power tubes anyway.

 

[Pegleg]

Thanks . I'll try having a swap around. I don't get any knocking or ringing from any of them, they all seem quite stable.