MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Somehow I eventually make it fit. The "clicked" part of your reply was the key :) In the attached photo I drew the shape of original mounting plate (yellow line). Your mount has straight groove but the mounting plate is bend to make a belt holding part. Hope it helps.
For now it holds great and I am happily printing again. Thanks.