You'll get more responses if you repeat this post in the LS section (or get it moved to there).
I don't recall there being an adjustment either. It may be that one of the tabs that holds the gear mechanism that latches the tray and damps its motion has broke. It happened on one of mine, but it wouldn't stay closed at all.
Have a look at it and see if there is anything that you can identify as broken and epoxy or melt it back together. Otherwise, your local pick-n-pull type junkyard or ebay would be the places to get another one. The local place will be cheaper than ebay, if they have any.
Edit: Sorry, you are talking about the top door and not the tray. Anyway, I don't think that really changes my answer.