salt problem?

i have a Bosch Exxcel dishwasher auto option i bought it of my mate and guess its about 5 years old.the problem is it doesnt use any salt and if i dont put it on a long wash with premium tablets itthe dishes dont get clean.It was stored for about a year so im guessing that the salt that was in it has gone hard and wont allow any flow through.what is the easiest way to unblock it ?????????????????? Rich