As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDING GEAR WILL NOT RETRACT AFTER TAKEOFF. RETURNED TO EWR WITH AN UNDERWEIGHT LANDING. FOUND THE LATCH AND PRESS WARNING CIRCUIT BREAKER TO BE TRIPPED. RESET C/B. JACKED A/C SWUNG GEAR IAW AMM 32-32-00 SEVERAL TIMES COULD NOT DUPLICATE PROBLEM. A/C OK TO CONTINUE.