Train doors at car 1517 'B1' were not proven closed. TC opened and closed a few times to clear fault . ~~~~~ CE: 1517 B1 Door isolated.  1517 B1 door checked found high resistance during manual opening/closing of door (18kgf). Further found grease was applied on J-rail, leading to build-up of dust. Cleaned J-rail, door leaf brackets/rollers. Readjusted shim on door operator joint bracket. Function check - OK. Force check at 8.8kgf with door leaf attached to door operator. Door cyclic test 20x & no fault occurrence.  Sarma/Kana. 13/03/2021.