Speedo drive washer

Changed the gearbox cover gasket today, only problem was when i took out the speedo drive and could not find the washer that should be under the drive. I am as sure as i can be that it has not disappeared into the box as i disembowled it to look, nothing looks unduly worn so is it really necessary?

I would say yes as it stops the speedo drive from eating it’s way into the casing

Yes I suppose it could do that, thankfully that hasn’t happened yet but i wouldn’t want to leave it out just to find out how long it takes. However I think i’ve found the washer, there’s one between the gear on the shaft and the brass housing that screws into the gearbox and i can see no reason why there should be one there so i’m guessing that’s it, fits perfectly where it should be.