If you put the washer on a screwdriver holding the washer, and put the screwdriver on top of the bolt it acts as a guide for the washer when you let it go for install
thanks for this! very useful for my first rebuild ever! on minute 12:35 to :40 it looks like the top of the chain got tensioned...how did you do that? passing one extra tooth for the intake side? thanks again: invaluable series!