A model number would be helpful. The only microwaves that I repair anymore are built-in models. For a do-it-yourselfer it might be worth fixing even if it's only a countertop model. Some parts like door switches or hv diode are very inexpensive. Control boards and magnetrons may cost more the microwave is worth. I almost always use generic parts on microwaves. They're just as good and a lot less expensive.