As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS AFTER TAKEOFF WHEN VNAV WAS SELECTED THE MAGENTA SELECTED SPEED WOULD NOT COMMAND AND DISPLAY THE FMS SPEED OF 250 KTS ON BOTH CAPTAINS AND FOS PFD. SPD INTV WOULD ALLOW 250 KTS TO BE DISPLAYED ON BOTH PFD. MAINTENANCE REMOVED & REPLACED #1 FMC IAW AMM. PERFORMED OPS CHECKS WITH NO FAULTS IAW AMM 34-61-00.