1. The slope resistor in the tone stack is a 33k. It's not legible on the schematic, sorry about that. The treble pot is a 250k linear as well.

2. You'll find that this is a very bright amp. Marshall knew it was going to be heavy on the distortion, so they boosted the highs and cut the lows. The evidence is in the .0022 coupling cap after the first gain stage, the .68 bypass cap and the .005 bypass cap on the volume control. Play with these things to get the response you want. But you won't want to add too much bass. It will get mushy real quick. That .005 bypass cap is a little intense. Try a .001 or even smaller. But remember, this cap does nothing when the volume is all the way up!

3. There is a 500pf cap bypassing a 470k resistor in the preamp. Try changing the value of this to tailor gain and tone characteristics.

To links.