This may have already been mentioned to you, I was at the USBC in Anaheim this year and on the show floor I saw a sweet rolling brush that reminds me of a mini mini street sweeper. I can't wait to order one. They were not quite on the market yet so the one I held was a display. The ultimate answer to cleaning the tray.
-- Ambassador for Specialty Coffee and palate reform.
a good shop vacuum will do the trick as well