Smeg SUK91MFX overheats and cuts out

My Smeg SUK91MFX often cuts out while cooking. Typical symptoms are the oven fans going off and the timer display going blank for a period of time. Strangely, the orange oven indicator light remains on and the oven remains hot for quite some time. The metal work around the top of the oven also gets very hot. Eventually the fans and timer will come back on but the time it takes varies from half an hour to overnight before it all comes back to life. I decided to pull the cooker out to gain access to the back in search of the model number, the timer came back on briefly but went blank after I had placed it back against the wall. There is no reliable CORGI registered engineer in my area willing to look at it so will have to have a go myself. Any information on what the problem is would be appreciated.