My MacBook (Model 1181) is in pristine condition, so getting a new one seemed wasteful. After doing an internet search on possible causes of intermittent track pad and keyboard failure, I found it to be a consistent problem with these models. I ran thru the prescribe checks and decided to change out the upper case cable instead of the whole upper case, $30.00 vs. $150.00 plus.
As with all thing electrical, sometimes connections need to be reseated, particularly in humid environments. This combined with warm up and cool down of the computer, over time connections may fail. I replaced the cable for good measure which corrected the problem.
iFixit's repair manuals are great. Following the step by step instructions and using the right tools, makes changing parts a breeze. With every Mac I buy, I at least keep a copy of certain iFixit repair manual for emergency use. Thanks, iFixit.com!!!
Hint: I placed double stick tape on some paper and place my screws in order of removal on the tap. I also made any notes to myself where needed. This made it exceptionally easy to find the right screw for the right hole on reassembly.