quick question for anyone who has rebuilt an f20!

[alan b]

http://file049b.bebo.com/14/large/2009/06/09/11/414601182a10997135890l.jpgtook apart two f20 yesterday as i have to make one good one out the two, and this washer fell out both times just as i pulled out the gear clusters, where does it go back in? is it for the reverse shaft?

[GRUNT 16V]

theres only 1 place it goes when you pull out the gear cluster it falls out all the time got a feeling its something to do with the reverse gear shaft??
if you look in the gearbox housing it goes on the right it can only fit in one place !! get a pic up of the inside of the housing !!!1