TM 10-3930-659-34 4-70. FORK/BOOM CYLINDER REPAIR (Con’t). NOTE Note position of wear rings, piston seal, and spacer to aid during assembly. 5. Remove two wear rings (12), piston seal (14), and spacer (13) from piston (3).  Discard wear rings and piston seal. NOTE Note position of backup rings and preformed packing to aid during assembly. 6. Remove two backup rings (10) and preformed packing (11) from piston (3).  Discard backup rings and preformed packing. TA708432 4-289