Deliberately made awkward. On reassembly the screws will go up from under
into the alternative existing unused vertical threaded holes of the front
sub panel. With a torch and mirror there are 2 screws access under the pcb,
horizontally threaded. The one under the treble control requires undoing the
toroid's coachbolt to get to. Even then required putting a pozi headed hex
piece inside a nut driver to be long and narrow enough to get to it. The end
one is ok when you know it is there.