Re: PIC24FJ128GB202 - using SCLKI for digital input.
Problem solved, but I don't know how!
Inspired by Howard Long's answer, I started a new project and put in the minimum code to do a test. It worked. So, I added back chunks of code and tested as I added. When all the code was added back it still worked!
So, I started another new projected, added copies of the original projects files, and it worked!
I am using MPLabX and XC16 v. 1.34 compiler.
I don't know why it works, but at this point I will use it and move on.