Where can I get that silver cardboard that fits in the side of the microwave silver crest ft I'm lidl

Hello Kate;

My name is Peter.

I am a retired field service appliance technician. It sounds like you have a bad element.

Go into the following website, put in your model number. You will get diagrams, part numbers and cost. Record the part number and search the internet for best price.
Water Filters Lawn Garden Appliance Parts

One thing to try is set it on its side or back or shake it to check to loose parts.

There is electrical problem in your microwave heating circuit. This is a fire hazard and you should stop using this microwave and unplug from the outlet. This is not something you can fix and the fuse does not protect your system anymore. The best choice is to purchase a new one and throw this away.

I am also having this same problem i dont know the solution yet, but when you figure it out please let me know, or if i figure out i will repost =]

It sounds like what you are describing is called a "waveguide cover". You can purchase a replacement from a local parts supplier, or on-line at www.repairclinic.com. It is very easy to replace.

the disk is just a microwave diffuser but, it is made with a special foil do not put regular foil into a microwave for any reason; just glue the disk back on with ordinary glue

No, that is the "waveguide cover".

It provides very important protection for the magnetron.

And always keep it clean according to your manual's instructions.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

It sounds like you may be talking about the wavegudie cover. Does it cover a square hole in the side or top of the caivty? If so, it is needed. It prevents grease and food debris from getting in the waveguide, which can damage the magnetron. I would refer you to Danby customer service: http://www.danby.com/page.asp?code=5