First - make sure the washer isn't modified or whatever in your buddy's workspace, or checked out.
If it is then re-add it to the workspace or undo checkout.
Then lock everything in the workspace. Actually you only need to lock the washer part and the generic for it, but select all and lock is easy. You can't lock new stuff and you can't lock checked out items. If I'm wrong about the new stuff, they can easily be unlocked on the File menu for the drawing.
You should be able to check in whatever is using that part.
DId this most every week for the past year. Same symptom, and I hope the same cure.