Actually, it's a piece of cake.
Take the (several, I can't count them now as it's taped to the floor) small
phillips head screws out of the bottom of the base. The pedals and springs
will fall out if you're not carefull when you take it apart. Nothing to be
scared of though, it's easy to figure out how it goes back together, and
there're not that many pieces.
Remove the brake and or throttle spring, and take it with you to the
hardware store. It's a very common size, and you should be able to find a
selection of stiffer ones. Put the whole thing back together using the new
(stiffer) spring(s) and try it out.
For the price of the springs (cheap!) you should buy as many different
weights/stiffnesses as you can find, so that you have a selection.
I changed the brake spring in my LWFF (Logitech Wingman Formula Force USB)
wheel before I even used it for the first time. I could tell right away
that the brake was way too light, and differed too little from the throttle
spring. I laid it upside down on the chair and opened my new as yet
untried pedal assembly to see what it used for pedal return springs. Lo and
behold! An off the shelf compression spring. I went straight to the
hardware store down the street and picked up the only spring they had that
would fit. A measly $.62 It turned out to be perfect, and I've been using
it to drive GPL ever since.
With the extra effort required to push the brake pedal (ooh, what feeeel!) I
found I had to tape (with 200MPH duct tape) the pedal unit to the hardwood
floor, and put furniture cups under the rear two wheels of my computer chair
to stop it from rolling back under hard braking. An added bonus is that
it's really easy to have the controls in a consistent position relative to
each other, the chair, and my view of the monitor. When I put the cups
under the chair, I can line it up with the pedal unit, by looking at the
boards on the hardwood floor, and I have a mark on the edge of my desk for
reference when I bolt on the wheel. Am I ***or what?
The separate axis for the pedals are also a must-have for serious GPL
control.