There was a question on replacement of a diaphragm and namely the module in different lenses can be identical? The fact is that the catalog of spare parts for the Canon ef 400mm 5.6L lens, the diaphragm module is indicated under the number YG2-0214 and as not strange the same marking it is specified for EF 300mm 4.0L and for ef 70-200 2.8L. I want to buy and replace it myself, if you know where you can buy at a normal price, including the used condition, please share.
If you feel comfortable manually repairing the unit yourself, you can order parts from our Jamesburg Parts Order Center. Bear in mind that, due to liability issues, we are unable to provide you instructions on how to conduct repairs. If you purchase a part, you assume the responsibility of replacing it. Also note that spare parts sold through the Parts Order Center do not come supplied with installation or set up instructions.
The best way to obtain a replacement is to contact Canon's parts department. If you contact them at the number and address below you will be presented with appropriate prompts for ordering parts:
Canon Factory Service Center
100 Ridge Road
Jamesburg, NJ 08831
Phone: (866) 481-2569
Business hours: 9 AM to 7 PM (ET) Monday to Friday