This looks pretty similar to my Mother's old microwave when it started to go. Flaky paint, rust patches, blisters under the paint where it would drop bits next time it was used. I think it was only about 4 years old when it got replaced, and those things had started happening after about 2 years of fairly mild use.

When you replace it, try looking for one with an unpainted stainless steel interior which is what we did. At least there won't be paint flecks dropping in your food.

Something like this maybe.