The lower nipple on my cooler was cracked and the reason new cooler lines didn't completely stop a leak. The correct drill and tap are expensive enough that they will pay labor if you don't have a drill press. An quicker fix is to replace the cooler if you have or can find a replacement.

__________________
85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.