Just like all revolvers in the "Hand Ejector" series this is a symptom of "push-off", when the trigger is so light that merely touching it causes the hammer to fall. The double-action sear catches the trigger because the trigger spring pushes the trigger forward enough for the D.A. sear to catch the trigger as the hammer falls.

This can be a result of wear to the hammer sear notch, the S.A. sear, or both. Improper /in-judicious work on those parts can be the cause too.

It is realistic at this point to accept you have a double action only revolver unless you are lucky enough to find a replacement trigger and/or hammer. Maybe JP@AK can advise you on parts sources.

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Gunsmithing since 1961