I have been collecting 38 s&w top breaks for years. Yours looks like a Euskaro that has been refinished, it looks like there is also a faint trade mark on the right side. Can you post a close up of that side?
Smith&Wesson top breaks where very popular in South America, the Spanish manufacturers took full advantage and made all kinds of knock offs, The most common ones were:
Orbea Hermanos
Euskara
Eibar (More than one manufacturer marked their guns Eiber because they were made in the city of Eiber. They were, Armeria Elgobaressa y Cia, Echealasa y Vincinai y Cia, Hijos de Angel Echeverria y Cia, and Iraola Salaverria y Cia)
They would mark them in very deceptive ways, the very early models would be marked with some variation of "Smill & Wilson Sprangfield, MUS EUA, " I have several that are marked like that , Euskaro changed its later production guns to a variation of " 38 Smith & Wesson ctgs are those that fit best the "euskaro" revolver". Or they say the "Eurakaro revolver is best with 38 Smith & Wesson ctgs". That is why I think you have a Euskaro. I have 5 marked just like this, and the font and position of the markings on the barrels are the same as yours. I think when it was refinished some of the writing was polished off, they usually had blued triggers, hammers, and barrel latches or some combination as well. With the later writing and font on it, it would put the manufacture date between 1899 and about 1920. They switched design around this time.
Your trigger also looks like a double action trigger that is not returning properly and that is why it is only working in single action, I have bought these in various conditions and with various types of "expedient repairs". It is common for them to only work in single action or double action but not both. It really needs to have the action gone over.
Small top break revolvers are weak by design, even in top condition, they were made to be carried more than shot.