TM   10-3930-643-20 FRAME AND TOWING ATTACHMENTS TROUBLESHOOTING AND MAINTENANCE. (cont) 11-1. Frame  and  Towing  Attachments  Troubleshooting. MALFUNCTION TEST   OR   INSPECTION CORRECTIVE ACTION a. PINTLE HOOK INOPERABLE. Pintle   hook   does   not   rotate   or   latch   will   not   open. If   pintle   hook   is   damaged   or   inoperable,   repair   or   replace   as necessary,   refer   to   paragraph   11-4. b. STEP,  LADDER  AND  RAIL  LOOSE. Check   mounting   hardware   for   tightness   or   missing   parts. Replace   as   necessary,   refer   to   paragraph   11-3. c . FRONT  AND  REAR  FRAME  SCRAPING  NOISES. If   the   front   and   rear   frames   are   coming   in   contact   with   each   other,   the center  hinge  pin  needs  to  be  adjusted. Notify   Direct   Support. 11-2