I have a Tricity electric fan double oven cooker but hardly ever use the large oven. My problem is this. I have had a mouse in my kitchen for the last few weeks and every time I try to trap him, he runs under the cooker. I have moven the cooker away to look but he is not there and there is no other way out as I have blocked all exits off. I turned the cooker on its back so I could see underneath, but all I could see was lot of dusty lagging, so I cleaned out all the rubbish with my vacuum cleaner, but couldn't see any sing of the blighter! He may,of course be in my vacuum bag but I have taken the precaution of covering the back and the bottom of the cooker with fairly strong plastic so I can see if he can get out of that. My concern is, is it safe to operate the cooker with the plastic on, as I understand it does not use outside air to operate the fans? Sorry to be so long winded but I wanted to explain everything 
