Tac dot on .22 pistol - Hi-Lux Optics Tac-Dot 21x16mm Tactical 4MOA Dot Red Dot Sights w/Integral Mount

The manual that comes with this sight does not mention the 2 small screws on the rear, facing the shooter, or what they are for ..I discovered that they are needed to lock the sights once they are set . I emailed Leatherwood for info some time ago but have not received an answer.
Last week as I set up for some practice I noticed the four screws from the base of the hood had fallen out...The hood still feels to be attached OK but I have attempted to find matching screws here in Australia but have been unable to do so ... Our top gun shop here told me I should try Leatherwood which I have done, but surprise surprise.............No answer..
I have a couple of other Leatherwood sights on other guns and never had a problem with them, but I don't understand what the problem is with Leatherwood now. I really do believe they should lift their game if they wish to stay in the scene.
Ken