Portable Dishwasher left haze on dishes

I just bought this dishwasher used. When I first got it, it made a bit of a crunchy sound when it ran. I found a 2 liter soft drink bottle cap at the bottom. I took that out and it quieted down. The first couple of loads were great, but now it leaves a haze on the glasses. There is also a rusty looking stain on the side wall and rusty looking residue on the racks in places. There were a few spots on the racks when I bought the dishwasher. I cleaned those, but now there are new spots on the racks, and I think the spot on the side wall is new. Any ideas about the cause? I have attached a photo of the spot on the side wall. Thanks for any help.

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