Canon YA2-0929 EF Screws
Genuine Canon collar retaining screws for the collar used in the EF 70-200 2.8 L USM, EF 70-200 2.8 L IS USM, and the EF 70-200 2.8 L IS II USM lenses.  Package of 1 screw. Made by Canon Japan.
The collar used with this screw is in stock here.
Canon YG2-2062-100 Power Diaphragm Flex
Canon YA2-2082 Stainless Collar
Genuine Canon stainless steel collar for the EF 70-200 2.8 L USM, EF 70-200 2.8 L IS USM, and the EF 70-200 2.8 L IS II USM lenses. Package of 1 collar. Made by Canon Japan. Need the screw used with this collar?
Canon YB2-3788 Lens Collar
Canon YF2-2027 Guide Key
Canon YB2-0033 Zoom Collar
Genuine Canon Zoom Collar for the EF 16-35 2.8 L USM, EF 16-35 2.8 L II USM, and EF 17-40 4.0 L USM lenses. Package of 1 collar. Made by Canon Japan. The screws used to retain this collar are in stock here.
Canon XA4-9200-606 EF Screws
Canon YA2-8001 EF Screws
Canon YA2-0124 Friction Rubber
Canon YG2-2062 Power Diaphragm
Genuine Canon power diaphragm assembly for the EF 24-70 2.8 L USM lenses. Made by Canon Japan. Unfortunately, this part has been discontinued and is no longer available.
TechNote. Many times the issue you may have with your lens points to the power diaphragm unit, when actually the FPC (flexible printed circuit) has broken and needs replacement. In stock here.