PRO-3 mods

[Dave Bradley <DaveB@datastorm.com>]

I have seen passing references in this list to changes in the
PRO-3's drivers and components since it first was released.
Can anyone enumerate what they were, and the reasons for
the changes?  My unit is numbered 1200-something - how do
I figure out if these changes are in my unit?  Are the mods on
my nickel or Motion Sound's?  Is there any adjustment to
increase the depth of the modulation on the bass simulator?
I can get enough volume, but it sounds sterile next to a 122
(yeah, I know, I know..., but more mod depth would definitely
help!)