Hi Kikemec, thanks I already managed to repair it, it is true it was an almost triangular piece that is taken with two screws and subject to a bench and on the other hand to the one in an end of the round axis of the trapeze.
I cost me a lot to disassemble the pieces, but it was easier to reassemble.
You know where I can get a Peugot Parnet workshop manual 1900 year 2002 71 CV WJY type