OK so I am not a player so help me understand.  I have repaired this amp.  I replaced both speakers with 16 ohm units in parallel for 8 ohms.  I think it had scorpians for 4ohm.  I do not have a footswitch to test with.  so is the saturation control even active w/o the footswitch.  Because I have doubled the load does that mean it will overload sooner because the output stage is running out of voltage.  I really am starting to think that there is nothing wrong just an overloaded output.
One oyher thing I come from the hifi world where everything is linear and undistortred.  There are2inpuys on this amp hi and low gain.  It says there is a clean and distorted channel activated by footswitch is that just signal path or the physical input.

I had lots of problems getting this up and running after setting in attic for years.  Replaced quite a few bad components but working ok now.  One last problem.  When I turn up the saturation pot I start to hear cracking sounds on hard strumming.  The more I turn it up the more cracking I get but not louder.  It sounds like a voicecoil bottoming out but I don't think that is what it is.  Tried it on another external speaker and it does the same cracking.  One thing I'm not using any footpedal not sure if it is needed to turn on and off.  When the Sat pot is all the way down everything sounds fine.