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.
 
the spring in the sight is larger and has way more power than a pen spring
i took mine loose the other day but could not unhook the front of the sight
the spring set far to the front but i wonder if the bearing ball has been lost
it is maybe 1mm and with that gone the screw will not index on the ball and could just spin
grease the ball to hold it place
bearing balls can be found on Ebay cheap