Waveguide cover for Moulinex microwave model DA4

Not sure whether this is a waste of time but am wondering if it is possible to replace the rectangular waveguide cover in my microwave.The cover has split in the corner where the ceiling meets the wall.
The section covering the ceiling of the oven is held in place by inserting the 2 corners into slits in the ceiling. Where the ceiling meets the wall, the guide then bends 90 degrees downwards to cover the side wall. This is held in place by 2 white plastic bolts (not sure how to remove this).
1) Is it still safe to use my microwave?
2) If I were to purchase a new waveguide cover, can I bend it without breaking it?!
3) How to remove the plastic bolts without breaking them
Thanks.