Northwest RV Supply has both the touchpad and brain (black box computer). See: http://www.nwrvsupply.com/Merchant2/merchant.mvc?
I bought both for $169 (total cost) from them and am keeping them as spares. The calibration is the issue. I, too, had mine re-calibrated (or as they say "flashed") at Beaver Coach Sales but they did not have to remove the computer to re-calibrate. They simply left it where it was (left side of driver's seat on the floor under the console) plugged it into a laptop and "flashed" it. It took about 20 minutes for them to do this. It has worked well since.
Another source for parts and re-calibrating is SunBumRV (
http://sunbumrv.com/). Rob Pierce (the co-owner) worked at Beaver when they installed this system and was one of the individuals that was responsible for this system. He is located in Yuma in the winter and LaPine, OR in the summer.
Final note: I was having a problem with one of the switches that determines if the jacks are raised or not and replaced the front two. As has been previously mentioned, the front ones are "relatively easy" to remove and replace. To replace the rear ones I will have to remove the wheels. Fortunately, the problem was with the front ones, so I am now carrying two new spare switches.
Bill