What would cause an Amana RC17S2 microwave to keep sparking everytime it runs?

[miltonsappliance]

some rc17 have 3 magnetrons and 3 transformers and caps if its sparking inside at top verify antenna is clean and turning if sparking on bottom look for burning on oven tray or if silicone seal is damaged if tray is chipped  or hot spot you will need to cut silocone lift up tray make sure bottom antenna is not damaged clean and turning you can take amp draw on each transformer using far left wire on the front of transformer I believe one is blue one is yellow don’t recall other mayby brown amp draw should be close on all 3 around 5 to 6 amps each do not run unit empty put plastic bowl with water to check another thing you could do is unplug left wire  one at a time on transformer run it do this on each transformer if sparking goes away the magnetron for that transformer will need inspection to get you by leave left wire unplugged tape it up I would start with amp draw first that will tell you a lot to begin with