I am pleased and relieved to report that I have successfully repaired this problem, and didn't break anything else in the process. I did it by replacing the pressure sensitive strip on the PCB. I ordered it from the Midi Store in Arizona. DenCV and Greazy Jim Alfredson pointed me in the right direction, and I found this video
on Youtube where the man makes an identical repair on a Nord. I'm now an expert at opening up my SK1 and removing the keyboard, which is actually very simple. Critical to the success of this repair is that you orient the replacement strip correctly. There are two little rubber prongs inside each sensor, which determines the volume of the struck key based on velocity. One is slightly longer than the other, and it should be at the twelve o'clock position when you place the strip into the PCB. Naturally, I got this wrong the first time and found that all of the keys that are contiguous and were using the new strip were equal in volume, but also equally louder than the rest of the keys on the keyboard. I waited till the next day to go at it again, and swiftly removed to keyboard and PCB to find that the strip was indeed opposite of the rest of the strips. I removed it, flipped it around, reassembled enough to test it and voila!, it worked perfectly. The old pressure strip did not look in any way damaged or different than the malfunctioning one, and no debris or soilage was visible. I am beside myself with joy that I did this successfully and saved myself about $200 plus bucks. Thanks for all of your input.