build a feed from my 3d cart web store for eBay and amazon. Store settings are already set.

Had a freelancer build a full store on eBay and amazon about a year ago feeds no longer work. Plus we added producst. store setup I want to keep the same but I need clean feeds to repopulate 250 products approximately. I have all old feeds. They just need to be tweaked so ebay accepts them and new products from my 3dcart store added.