What was found
WHEN PUTTING FLAPS FROM 20 TO 25, TE FLAP DISAGREE EICAS WARNING CAME ON. FLAPS STAYED AT 20. WENT AROUND & FOLLOWED QRH. RETURNED TO AIRPORT FOR UNEVENTFUL 20 FLAP LANDING. TROUBLE SHOT SYS IAW FIM 27-51 FT 808. FOUND NO FLAP OVERLOAD INDICATORS TRIPPED. INSPECTED ALL FLAP TRANSMISSIONS FLUID LEVELS & FOUND LT INBD FLAP TRANSMISSION FLUID LEVEL LOW. SERVICED LT INBD FLAP TRANSMISSION IAW AMM 12-13-06-3. ALSO LUBRICATED ALL FLAP SYS IAW AMM 12-21-09-3. CARRIED OUT FLAP SYS OPERATIONAL CHECK IAW AMM 27-51-00-5. ALL OPERATIONS SATISFACTORY. OK FOR SERVICE.