Beginning in October 2016, a few months after the latest book was published, the Museum changed its hours for positive results. It is now open on Sundays, too. Fortunately, I was out walking before my tour and saw the change.
On Sundays at 1:30, you can meet in the same Close for a 90 minute "Book Lovers' Walking Tour." led by Allan Foster, author of The Literary Traveler In Edinburgh & The Literary Traveler In Scotland. The cost is 12, but 11 for students and seniors. No reservations.