I own a phillips Pronto which I edit on the PC with pronto edit version 1.5 . I also play around with the Marantz RC500 version 2.2 . This version has a function which lets you jump to a specific point and then return again after setting a suitable delay . Having made these modifications my pronto edit 1.5 will not open the file up as it states it is not a valid pronto file . Can I overcome this .