I waited too long on my 2008 before I finally did brakes last year. In addition to the magnets and shoes being worn, I had to get new drums also bcause they were badly scored. (Sidenote: nobody cuts brake drums anymore....had to buy new ones.)
eTrailer had a kit that included the self adjusting brake assembly, the drum, new grease seals, new bearings and new lug nuts. Didn't need new bearings but was cheaper to get the whole kit. Since I have the nevr-lube axles, they use the tang washer instead of the castle/cotter set up ,and I like to replace those as well just so the tang doesn't break off from being bent back and forth.
To the OP, also check and refresh all your ground connections by the tongue to be sure you are getting max voltage to the brakes.