Does anyone have any tips on how to get rid of smells in a microwave. I've tried heating lemons in it, used the foaming cleaning pads from Lakeland, wipe it out all the time and always wash the turntable but it just stinks. I hold my breath every time I open the door, it's that bad! I can't put my finger on what exactly the smell is, just generally nasty. Or should I just give in and buy a new one?