Random washer while changing out timing chain on 02 400ex

Hi all. Thought i was already a memebr but guess not. As the title says i am replacing the timing chain on an 02 400ex. Removed the cover, clutch assembly, and oil pump. I removed old chain and replaced with the new chain (02 crf 450). While everything was out i grabbed a rag/paper towel that i had by the machcine to wipe out the oil from the bottom of the case when i hear what sounds like a small piece of metal drop and i see a small washer sitting on the bottom of the case. Problem is im not short a washer?!? Possibly it could have been stuck on the rag but i didnt remove a washer that looked like this. Ive been through the manual, parts schematics, forums but still no luck. Everything is back together minus putting the case on and im not missing anything (i think). The OD is 3/4", the ID is 7/16" and it is a little thicker than the avg washer. One side is completely black and the other side has a small silver ring as you can see below as if it seats on somthing smaller. Thank you in advance and any help is greatly appreciated!

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Random washer while changing out timing chain on 02 400ex

Hi all. Thought i was already a memebr but guess not. As the title says i am replacing the timing chain on an 02 400ex. Removed the cover, clutch assembly, and oil pump. I removed old chain and replaced with the new chain (02 crf 450). While everything was out i grabbed a rag/paper towel that i had by the machcine to wipe out the oil from the bottom of the case when i hear what sounds like a small piece of metal drop and i see a small washer sitting on the bottom of the case. Problem is im not short a washer?!? Possibly it could have been stuck on the rag but i didnt remove a washer that looked like this. Ive been through the manual, parts schematics, forums but still no luck. Everything is back together minus putting the case on and im not missing anything (i think). The OD is 3/4", the ID is 7/16" and it is a little thicker than the avg washer. One side is completely black and the other side has a small silver ring as you can see below as if it seats on somthing smaller. Thank you in advance and any help is greatly appreciated!

Attached Thumbnails

Click image for larger version

Name:	image_1469589993081.jpeg
Views:	N/A
Size:	696.7 KB
ID:	49938