So if you were able to put locators on there and get rid of the bar and the new one snaps on and fits well, then the gap should be an easy fix where you can just do a reline of the denture and have the lab correct it so that you can have proper tissue support with no gaps. Again, when you do this kind of thing, I would always communicate to your lab on what they need from you to achieve their best work as many labs Will have different requirements and you want to be on the same page.