Have read many posts about the track system in the 4200XL. One broke the other day on me and I got inside to figure it out.
Seems there is just a shear pin in there, the rest is all metal and heavy duty. Of course this does nothing to change the speed, but if you are in a locale where parts are not readily available, this thread should be of assistance.
I have never done Picassa before, so have patience.
Turns out that 3 screws were loose in the gearbox to the motor also, these got locktite.
You do not need to take off any more than the track, do not remove the part that holds the motor and sprocket.
There are 4 set screws, two on top, two on front that hold the motor assembly in place. Loosen them. (No photos of this) Remove the cap over the motor (inside part).
https://picasaweb.google.com/1064737...85097387688866
Well don't seem to be able to figure out and cannot find the thread on how to!