Hello,
The cooker that comes with the Oceanis 40 is model Gascogne by the French company ENO. The exact model is "RECHAUD FOUR 2 FEUX GASCOGNE 1823 depuis 12/2006".
If you go to their site you can select the pieces you need and even you can place an order. I have done that but I only received feedback after calling them by phone. The first pieces that I ordered were these. I ordered them from Accastillage Diffusion Spain.
Last year I ordered from SVB Germany the 2 burner cups and one spillage sparking plug. The new burner caps made a difference, not for the new nice looking but for the smoothness of the burning. To chose the parts I used the pdf document available at SVB and reproduced below.
Regards, Luis