Inside my microwave is a small 3x5" opening which is covered by a 3 x 5" piece of thin shinny cardboard. At one time, the four corners of the cardboard fit snugly into four small slots, so that it barely covered the full opening. Now those four corners have become broken and worn, allowing the cardboard to slip 1/4" below the top opening. Will this affect the performance or safety of the microwave? If so, can I replace the cardboard with a piece of non-shinny cardboard?
Thanks. digger