You might read the writing on that “Red Tab” component just below the fuse,
then Google those letters and numbers to see if it is a MOV (metal oxide varistor).

MOV do go bad from time and heat,
and if it has gone bad by having too little resistance to ground, that alone could cause the fuse to blow.

It is more likely that the 24 V wires have a short through dry/cracked insulation to ground,
or a contactor coil has an internal wire to wire short.

If you have a magnifying glass
look everything over for tiny black burn marks (aka carbon tracks)
and/or cracked insulation.