Hey everyone! Brand new to this site and this is my first post. Appreciate any advice on this!

Bought this amp used on Craigslist for $160. Every so often the sound gets incredibly muddy, sludgy and distorted. it will play fine for a while (20 mins)after first firing up
then all of a sudden out of nowhere starts to get muddy especially on the lower strings even on clean settings. Im guessung it has something to do with the speaker or speaker connection but really don't know as I'm a complete rookie with amps.

I've tried spraying all the input jacks with CRC electronic cleaner
I replaced the tube with a brand new one (12ax7 EH)
Tried a factory reset
Tried different guitars/cables

The vfs2 foot switch provided is finicky too-sometimes will work, sometimes not

The thing I don't get is how out of nowhere the sound starts to change so drastically. Is there a relatively cheap way out of this? Anyone else experienced this with this amp? I'll post a video of how it sounds.

Here's the video
Keep in mind: yes it sounds terrible. I was purposely playing notes and chords that sounded extra shitty.

Quote by diabolical
Sounds like you have an intermittent component, so I don't know, you'll have to take it to tech.

Thats definitely a possibliity.
Sounds kind of like a blown speaker, but since it only starts doing that after 20 minutes of playing, that eliminates that.

But I gotta agree with diabolical , intermittent component, most likely an electrolytic capacitor.
You could take it to a tech, but that may cost more then the amp is worth. But thats your call.
Most techs charge about a $60 bench fee (which basically gives you your first hour), and then an hourly fee.of who knows.
Last edited by CodeMonk at Jan 29, 2017,
Thanks everyone. Really appreciate the responses. I guess an intermittent component isn't something I could fix myself with my limited knowledge. I wonder if that's why the foot switch is intermittent too....same problem?
Just found on a forum from an amp tech: (mine is the VT50 but maybe its the same problem?)

I have fixed several of the VT-30 models. The issue with all of them has been that an electrolytic capacitor with the wrong value (.47 uF) is used in place of a 0.1uF Ceramic capacitor in either c17 or c16 right side of the power amp chip just in front of the green resistor. Some of the amps I've fixed, this capacitor literally exploded spraying paper pulp and melted metal around the inside of the amp. When that happens, the output is very low and distored, because only one side of the output is generating. In other amps, the problem is hissing and squealing, but the capacitor appears intact. They always test bad after removal. I replace them with the CORRECT value CERAMIC capacitor and the problem is much improved. 
I have been unable to find any other reference to this defect. 
Quote by bradym319
Do you think that would be a costly fix?

if you are handy with a soldering iron, $3.

if not i have no idea.
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youre just being a jerk man.

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