I removed the transmission this winter to change the rear main seal and I also changed my kickdown cable as well as the transmission oil filter. I removed the filler tube which was a PITA and in the process I damaged the threaded female "connector" for the filler tube on the oil pan. I changed the oil pan and now I am trying to put the filler tube back but it's still a PITA to reinstall it. So I think the threads on the filler tube might be damaged, but visually they seem fine.
I know it's a common problem removing the filler tube but what about putting it back? What do you guys do? Is there a male and female tap I can use to reform the threads on both parts?
What secret do you have to reinstall that part properly.

I am tightening and it's very difficult. And also when I get to a point where it's really hard to tighten there are a few threads left to go and the filler tube is able to move so I know it does not sit properly in its location.

What is the best thing to do?