Now, look, This is an observation, rather than a criticism, and I would like others to comment. There appear to be washers under the heads of the bolts. Now as has been stated many times recently, the bolts and threads in the banjo are supposed to be a good tight fit to help prevent leakage. So I would think that the bolts should be removed one by one, the washers removed, the holes cleaned and de-greased, but not retapped and the bolts refitted without any washers. you might add a smear of sealant if you want.
How does that sound??
Mart.