As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED THAT DURING GEAR RETRACTION THE RT MAIN GEAR WOULD NOT FULLY RETRACT. A CONSTANT THUMPING NOISE WAS NOTICED. THE GEAR CYCLED DOWN AND ALL 3 SHOWED GREEN. THE CREW ELECTED TO RETURN TO DEPARTURE AND LANDED WITHOUT INCIDENT. THE ACFT WAS REMOVED FROM SERVICE. FOUND BAD LANDING GEAR SOLENOID VALVE AND INSTALLED SERVICABLE VALVE IAW AMM 32-33-04. THE OPS CHECK WAS GOOD. THE ACFT WAS RETURNED TO SERVICE.