An alternative to trying to de-bend a threaded ring or to re-cut a damaged thread is to simply mill-off that damaged part. Would not look nice but most probably will come out as the technically better working solution.
I wouldn't have a clue how to do that, I can't even trim my nails properly! But sounds just the bomb for those willing to tinker. But for me, if I bugger a filter, I buy another one, learning solidly from my mistake.