A tip for those who don't already know. I figured that since the bleach in sepia toner (looks like Iodine to me and that makes sense - I knew that chemistry degree would be useful one day ) bleaches silver from prints it may do the same for other silver deposits.
So I tried it on my dev tray, a very dilute solution left for an hour or less leaves the dish looking like new. Works on measures as well. Like I say the old hands probably knew it already but it's nice to share with other newbies.
Cheers ; Chris Benton