A crappy fact about revision B motherboards is that they come with
weak simm slots. They are made of plastic, entirely. If you are not
careful when inserting/removing simms, you could easily damage a slot
by breaking off some plastic. Later revisions of A4000 motherboards I
think came with better slots, which looked something like what you
would find on most of the popular accelerator cards.
A steady hand could easily desolder the old crappy simm slots and
replace with the new (better) ones, according to my ex Amiga
technician friend, however I would not have the balls to venture
into something like that. :-)