Tuning Air Venturi V10 sight keeps losing height adjustment.

My Air Venturi V10 single stroke pneumatic air pistol is great… BUT the sight height adjustment screw does not stay in position, after each shot it needs touching back up.

I believe this is due to the spring that pushes up against the rear sight assembly being too weak or worn out to maintain proper tension against the sight.

Does anyone know what spring that is, or if it is a replaceable part? Maybe a part number from AV?

From a limited Google session I’ve found a rear sight assembly, but can’t seem to find if it includes a spring.

Thanks for the help.