[Joe Rossi]

 You may have to remove the record changer to get the amplifier chassis out of the unit, sometimes there are some screws that will loosen off to allow one to lift the changer out. I would guess that you removed the knobs from the amp chassis and did not find any other screws holding it in, perhaps hidden by the knobs?
Regards
Arran

Thanks Arran.  I hadn't tried that but I will.  I have taken the nuts off the volume and tone controls, but they ended up not actually attaching to the cabinet.  I hope your solution works!  I'll try it tonight when I get home.  Joe