Manual focus adapter problems

Nothing serious, but, on two occasions now, and with different types of adapter, I've had the flange that mates with the lens become loose from the body of the adapter. As might be expected, this results in out of focus shots, and that's the way that I have been able to identify the problem. Unfortunately this also means some spoiled images.

I now carry a small precision Phillips screwdriver that I can use to tighten the fixing screws. I guess a drop of loctite would provide a more permanent solution.

Sigma lens - Dodgy Contacts

I've had trouble with my Sigma 19 mm lens not responding when attached to my Sony mirrorless cameras. I was concerned that this was a warning of imminent failure, but, to date, cleaning the contacts has cured the problem.

I've tried cotton buds and that appeared to do the trick for a while, but after the latest episode of non response, this was not enough.

As a measure of last resort, I used the buds in conjunction with some Eclipse E2 sensor cleaning fluid. This worked, and saved me the cost of a new lens - I believe that Sigma regards these budget lenses as being disposable, and don't offer a repair service ( please correct me if that is wrong!).