Sorry for the late reply, but last week I was out of the office without access to mails, due to the Milan trade fair.
After checking your drawing, the provided measures correspond with an HMI 10 / 11 instead a 6/11 one. I know that you don´t have the model and serial number, but without this information is not possible to be sure 100%.
Maybe it could be possible to find any information about this oven like the invoice so on.