Neff built in circotherm electric oven

Model GB-1038.11 HCFG
E-Nr. 195.301 567

My oven is about twenty years old and apart from having the element replaced a couple of times has always been reliable. Over the past few months it has sometimes been making a noise which we have located as coming from the cooling fan. We have removed the fan, cleaned it and put it back and the problem seems cured for a few days and then it comes back.If you open the back of the oven and move the fan slightly the noise will go away again only to come back again later. The oven is still working.

Something seems to be catching and we are considering replacing the cooling fan if we can find one. Does anyone know if this is available still?

Thanks for your help.