Wilkins Repair and Maintenance Manual here
Repair and Maintenance Sheets and exploded views of their assemblies. Most individual parts are available although I heard rumor that as of January 2018 they will not sell individual parts any longer.
Exploded views also have the repair kits listed with them.
Double Check Assemblies
950XL 3/4" - 2" Exploded View Maintenance Instructions
950XLT / 950XLT2 3/4" - 2" Exploded View Maintenance Instructions
950 2 1/2" - 10" Exploded View Maintenance Instructions
350 / 350XL 3/4" - 1" Exploded View Maintenance Instructions
350 / 350XL 1 1/4" - 2" Exploded View Maintenance Instructions
350/350A 2 1/2" - 12" Exploded View Maintenance Instructions
350AST 2 1/2" - 10" Exploded View Maintenance Instructions 2 1/2" -6", 8" - 10"
450 2 1/2" - 4" Exploded View 2 1/2" - 4", 4" - 10" Maintenance Instructions 2 1/2" - 3". 4" - 6", 8" - 10"
450ST 4" - 10" Maintenance Instructions 4" - 6", 8" - 10"
Freeze Protection Information for 950, 950XL, 975, 975XL
Obsolete Double Check Assemblies:
550 3/4" - 6" (Rubbers only, except what suppliers have on the shelf). 950 (3/4" - 2"), 950 (2 1/2" - 10") Parts are available for the 950's in both size groups.
Parts available for obsolete double checks
Reduced Pressure Assemblies
975XL / 975XL2 1/4" - 1/2" Exploded View Maintenance Instructions
975XL / 975XL2 3/4" - 2" Exploded View Maintenance Instructions
975 2 1/2" - 10" Exploded View Maintenance Instructions
375 /375XL 1/2" - 1" Exploded View Maintenance Instructions
375 / 375XL 1 1/4" - 2" Exploded View Maintenance Instructions
375 / 375A 2 1/2" - 10" Exploded View Maintenance Instructions 2 1/2" - 6" , 8" -10"
375AST 2 1/2" - 10" Exploded View Maintenance Instructions 2 1/2" - 6", 8" - 10"
475 / 475V 2 1/2" - 10" Exploded View 2 1/2" - 3", 4" - 10" Maintenance Instructions 2 1/2" -6" , 4" - 6", 8" - 10"
475ST Maintenance Instructions 4" - 6", 8" - 10"
Obsolete Reduced Pressure Assemblies:
575 3/4" - 6" (Rubbers only, except what suppliers have on the shelf). 975 (3/4" - 2") 975 (2 1/2" - 10")
Freeze Protection Information
950,950XL, 975, 975XL 1/2" - 2"
Pressure Vacuum Breaker / Spill Resistant Vacuum Breaker
720A 1/2" - 1", 1 1/4" - 2" Exploded View Maintenance Instructions 1/2" - 2"
420 / 420XL 1/2" - 1" Exploded View Maintenance Instructions 1/2" - 1"
460 / 460XL 3/8" - 1" Exploded view Maintenance Instructions
Pressure Vacuum Breaker Video
Winterizing Pressure Vacuum Breaker Video
Discontinued
420, 460 (Parts available)