Well, Teejay.
First, try another example. What you did
is assign the first LFO's RATE to
the Mod lever, so if LFO1 isn't used to
modulate anything in you're patch, you
won't hear any difference by changing it's
rate, right ?

I suggest you tried by initialising
a user patch with the usual procedure
(Utility + Initialize patch). Then assign
set Mod Ctrl 1 to Cut (Filter Cutoff)
with a value of -63. If you don't hear any
difference when pushing the lever, then something's wrong with your 305.

Have fun !