With safety glasses on, use a fine Dremel cutting disc and cut 3mm off the 2.5mm end of the shock shaft.
Using DuBro (part# 2104 shown below) replace washer, piston and nut. This nut has no nyloc so you must use blue loctite and allow to dry over night before rebuilding shocks.
Remember, these nuts have no nyloc. You must use blue loctite to secure nut.