There's an accepted way to clean that bronze filter, and you haven't done it yet.
1. Find a large flat rock
2. Place bronze filter in the exact center of the rock
3. Using a 3-lb. hammer, take a full overhead swing, and hit the filter.
4. Repeat step #3 a minimum, of 3 times.
5. Buy and install a new filter.
Sintered bronze filters ARE NOT intended to be "cleaned". They're a throwaway item.
Jerry