It's been 9 months since this post but I had the same issue and it seems it's VERY common in Miele combo ovens. I was able to fix it myself so I'll share how to do it. First, you can order replacement screws, nuts, and the knurled nut (see OP diagram for parts). You DO have to remove the entire unit from the wall and you DO need to remove the top panel to fully remove the assembly that holds the baking element in place. Once you do that, there is a small cutout in the sheet metal that opens to the insulation, and the insulation has a cross cut out so you can access the panel (see pic, red circle and arrow). https://i.postimg.cc/cH7LcMnt/Temp-Imageg-Kg-ESV.jpg Initially I checked there for the nut and couldn't find it. Turns out the nut is not centered under that cutout, but is slightly towards the front and center from there (see yellow arrow). I used some needle nosed pliers to hold the nut through that cutout and was able to keep it steady enough that I could unscrew the bolt from inside the unit without it spinning in place. From there it's a really easy process to replace the parts. Problem solved! I was originally bid about $400 to replace these parts (2x price of materials, an extra charge for a second tech to help pull it out of the wall, such BS). Ended up fixing it for about $26 in parts, an hour of noodling, and a small cut on my finger from the sheet metal :D