Thanks- I was super bored the last weeks and ran across it.

Yeah, that note saying if you lose the washer you need a new head is scary. Based on that language, and Sunny's comment one of his injectors had two washers, it seems they had a number of depths and had to add an extra assembly step to measure and fit the correct number and thickness of washers- something they don't want to deal with as a maintenance item. It doesn't mean the OP can't measure and have a shim made. It's going to be a pain in the ass without the washer, but it can be done.