Vintage Halloween Party Invitation Opens Up Grandfather Clock USA

I was initially excited when I saw this listing, then I realized that it is missing the mechanical piece that should be present between the front and back. This piece was meant to move both to the left and to the right sides revealing spooky imagery. (See page 124…) One complete example sold in my March auction for a record $3,600, so the missing component has a major bearing on value. Even though the remaining invitation looks great - what is missing is important.