TC reported train doors not proven closed with obstacle detected at RDT B2 door. TC recycled doors o nce - OK. SM(CCK) checked and confirmed RDT B2 door faulty. Proceeded to isolate affected train door. ~~~~~ 3623 ER & fault trace D/L - Done. No FOD found. Before cleaning j-rail, LHS - 6.1kgf,  RHS - 6.2kgf.    After cleaning j-rail,  LHS - 4.6kgf,  RHS - 4.8kgf.  Sarma. 20/08/2020.