Note that beginning the week of April 29th, Billboard changed the issue date from Saturday (27th) to Monday (29th) and reducing the difference between chart dates and issue dates from 10 days to 5 days.
Note the ties where specified as such. This was common until 1960, where Billboard would use "a more accurate charting system to assist the ranking system" as Weekly Top 40 puts it.
Also, the issue date of June 17th marks the final appearance of the “Most Played In Juke Boxes” chart, and during the next week, 1) The Juke Box chart is discontinued; 2) The Best Sellers In Stores Chart is expanded to 30 positions; 3) The sales chart and sales portion of the Top 100 chart panel is revised and expanded. The “Best Sellers In Stores” chart is expanded to 50 positions on the issue dated November 24th.
For more info, see here: https://weeklytop40.wordpress.com/ http://billboardtop100of.com/
