My first suggestion if the brake are already adjusted properly and still dont work would be that possibily the cable is stretched and dosent have enough tension any more. If you do replace the cable though it's a good idea to do both or all three at the same time so they all wear the same. As for the front brakes I just redid mine along with new bearings and seals, and all new cables as my backing plate was broken and it was pretty easy. Really just a couple of springs hold them on after you get the drum off which is just a castle nut. Just remember to use a new cotter pin and clean everything up good.