OK thanks. I found the internal latch. As a quick test of the locking ability, I physically moved it 1" to the right and it locked in place. So I get that this is supposed to latch automatically when cleaning. Next steps are where I got stuck before and again just NOW:
1) When I press AUTO CLEAN, the display lights up "cln" and says "START?" CLEAN TIME.
What are the next steps? When I click START I get E1 -F5-
When I try things about setting time to clean, nothing I try works.