As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PROGRAM BUTTON ON CAPTAIN'S FMC/CDU TAKES EXTRAORDINARY EFFORT TO ACTIVATE. ACFT GROUNDED. UPON INITIAL EVALUATION, FOUND THE PROGRAM BUTTON TO FUNCTION NORMALLY AND TAKES NO MORE EFFORT THAN THE F/O'S. CLEANED WHAT APPEARS TO BE SOFT DRINK RESIDUE FROM THE CDU KEYS. CDU FUNCTIONS NORMALLY, REF MM 34-61-01.