Doug:
If the previous fix only lasted for a couple of times as you say, then either the replacement pins were too soft or not large enough in diameter. A tight fit of the pin in the pivot holes should last for years, its not something that requires smooth movement. They should be tight enough to require a bit of effort to move them into position.
As to punching the pivot, you need to locate what is too loose. If its the leaf punch it, if the axel is too loose in the base then punch them. if all are loose punch them all. If all are too loose then the axel is too small, as alluded to in the above paragraph and I would replace the axel instead of messing with punching, which will slightly deform the sight.
Bob