Marshall 8040 Valvestate problem ?

[fair.child]

Hi folks,

I've got a quick question here about my marshall 8040 valvestate. My question is, I've got good clean channel with my valvestate, it works, however the one that doesn't work properly is the Boost channel. How do I get higher volume from my boost channel. It's not loud enough like clean channel

Here's what I did before;
1) Changed all the pots with same value
2) Sprayed contact cleaner to audio jacks and other jacks
3) Changed tube with newer tube

I've tried to make this video

http://www.youtube.com/watch?v=igDej-pnY8o

However, I did that with second channel with full volume and gain. I believe that should be louder or have a same volume level like First channel. this is an issue. I couldn't get loud volume of my input whenever I press BOOST section. I thought that was a tube problem, but it didn't work, still have a same issue. I also changed the pots, all of them and still it didn't work. I can get louder output from my 1st channel or normal channel. How come I couldn't get higher level of volume in my second channel / boost channel, 40W it should be more than loud enough

As usual, any advice and comments are welcome. Thank you for your thoughts and advice

[PRR]

Clean readable schematic?

[fair.child]

Clean readable schematic?

only this one that leads me into schematic

http://www.drtube.com/schematics/marshall/8040-iss6.gif

[PRR]

That's a blur.

Wild stab. These amps use a special opamp chip with an on/off control to select either of two inputs. They are known to fail. IC30 or IC3B seems to be one. Part number blur might be 5281. (Not the TL072, 1458, or the TDA lump.)