Diodes are rated for the wattage, or amperage that they will be allow to pass, or breakdown safely within the component. Some of them may look alike on the outside, but their internal characteristics may not be the same. Pretty much like a fuse. You wouldn’t use a 1 amp fuse in a circuit if the transformer in front of it is constantly putting out 10 amps. The existing fuses may look alike, but the 1 amp fuse would blow every time the circuit was turned on. Read the label. Usually your HV diodes will be marked also. However, that is when you will have to research the specs on that particular diode. Depending on the HV capacitor, a CL01-12 diode will usually handle about 12 KVolts at a maximum of 350 mAmps. Many of these type diodes are common in the lower powered Microwaves. However, as the wattage of the newer Microwaves gets higher, the HV diode must meet the requirements of the circuit to work without breaking down too early, or failing entirely. I have seen some of the higher rated Microwaves blowing the CL01s, and working using CL04-12 diodes only rated at a little higher, 450 mAmps.