The top is held on by some bolts into brackets attached to the wood base one front, two at the rear.
No volume control (though I could do with them) just a large knob on the hum balance pot, the 'bracing' is purely decorative to cover the double holes for mounting the iron, just thought it looked neater.
Nothing to drastic, I had/have issues with hum levels (though truth be told its probably more due to my sensitivity as others don't seem to feel it's too bad). Paul J suggested increasing the capacitance in the high-voltage power supply, may give a small improvement, also added a Hammond 15 henry choke, as again PJ suggested this allowing me to move the original choke for power supply duties. Replaced 0.1uf capacitor between 9 & 7 with the Soniqs, because I had one of that value, last but not least mounted a switch on the top plate to toggle between 4 & 8ohms - so not so different from stock really!
Sent a couple of emails to MagneQuest about getting some 'real' iron but no responses yet - I suspect my emails may be a casualty of a firewall filter or some such manifestation :-( still no real hurry, it'll all get sorted in the end.