TM 10-3930-659-20 6-35. HYDRAULIC OIL FILTER RESTRICTION SWITCH REPLACEMENT. 3. Remove hydraulic oil filter restriction switch (5) from hydraulic oil return filter (4). 4. Remove    two    preformed    packings    (8)    from hydraulic oil filter restriction switch (5).  Discard pre- formed packings. b. INSTALLATION 1. Install two new preformed packings (8) on hydraulic oil filter restriction switch (5). 2. Install hydraulic oil filter restriction switch (5) on hydraulic oil return filter (4). 3. Install terminal lead (6) on hydraulic oil filter restriction switch (5) with nut (7). 4. Install hydraulic oil return filter (4) on hydraulic reservoir (1) with four washers (2) and screws (3). FOLLOW-ON TASKS: • Close left engine upper sideshield (see TM 10-3930-659-10). TA707819 6-135