Hi lecure,
My apologies for answering in English, French is however a bit too hard for me.
Your F1 has the old firmware, also know as OLDARCS. This system, with M99 J & K being defined as start and finish of the arc in degrees, is not supported by MFI.
In the NEWARCS system the parameters I, J & K represent the center coordinates of the partial arc. This is the system that MFI uses.
It is my understanding that it is just a matter of replacing the eproms of your F1 to get the new firmware (with more new features).
Hope to be of any help.
Kind regards,
Henk