Fitting Base Element for SMEG DO4SS-5

Question

http://www.fixya.com/ThreadView.aspx?thid=1382771&prdid=0

Following on from the above problem I purchased a base element (turns out the grill element in the base oven was still working). Now I can't figure out how to replace it or if it even uses a base element. Is the fan element the problem? Any ideas?