Can You Help Me With My Home Sub?

Hi, So i have a Cerwin Vega LW-12 150 watt sub. One day i went to use it and it crackles really loud. I am looking to fix it (without taking it to a pro). Its not worth that kind of money. I am wondering what in the amp could have gone bad though. Like what compactors and is the transformer gone and stuff like that. Any help is appreciated and i will check back to add more information if needed. It isnt a ground issue either and i have used different subs and amps so its the sub and not my equipment.