This problem is a trip back to the 1970s for me, remembering those low price not so good Spanish doubles that hit the shops here. The steel used was a little like toffee, so it was either the strikes turned into Mushrooms or the hammers had deep indentations where they hit the striker top.
My cure for the hammers was simple with them being soft I would file a recess in them at the striker position, then hard solder a piece of HSS (high speed steel) into the recess and grind to shape. A word of caution if the striker steel was not up to a decent standard you would end up with mushrooms in time, so I did replace the strikers as well to stop a return problem causing more work. But striker replacement in this case may not be necessary. In the way of gun faults this is a simple fault needing a simple repair.
