Replacement power relay for convection oven
Its a MOV, not a diode. Read the data behind (probably 275 volt or similar, size is also important, measure the diameter) or when buying a new contactor look if it has in-bult suppressor, or just unsolder it and reuse it.
Any power contactor with rated current contacts will do the job, as you said 21+14 = 35A or more some standard 40A, or two separated contacts 25A...
The correct coil amperage isn't important (the coil voltage is important), it will be almost the same for the same size of contactor.