Hi Teemu. I'm no photographer I'm afraid but hopefully these will help. This repair was a while ago but from memory, I originally used contact adhesive to glue the hook back on, but it came off again - because it's only small, there isnlt much surface for the adhesive.
So, second attempt, I made a little triangular plastic 'buttress' - a right-angled triangle of only about 3 or 4mm high, out of a hard plastic (I think I made it out of a broken cassette base, using a craft knife.
I glued that onto the 'hook' first, and then I glued the hook in place, but this time I used superglue gel, and I used quite a bit of it too, hoping that the gel would dry into a 'blob' that would help hold it all in place. Happily, it worked.
It depends where yours is broke - on mine, the hook broke so that there was a rough area on the lower-right side (opposite side to the hook itself), which meant I had to glue it onto the right inside edge of the round hole on the carriage, where it had broken off from. I had to allow for this when I attached my makeshift 'buttress', making sure the bottom edge of my buttress, and the right edge of the broken hook, formed a small right angle, which I could glue into place.
I'm afraid it's not very clear on the photographs (the buttress is made of clear plastic so you can't really see it), so I've added a little diagram:
The grey part is the carriage, and the gap is the little round hole that the hook broke away from. The blue is the hook, and the orange is the little buttress I made from a piece of hard plastic. Remember I glued the buttress onto the hook first, let that dry, then glued the hook and buttress onto the carriage.
Hope it helps.