Joining the Delta Link tool is a very handy AST 5408 service light reset tool. I’ve never used one — or seen one — so I can’t comment on particulars, but in roughly two weeks this little gem will be available to borrow.
It resets the Service light on 850s.
It’s being donated to the program by a wishes-to-be-anonymous MVS member. I’ve thanked him in private correspondence, of course. Things like this make me so proud to run this site.
UPDATE July 1: It’s here.