I've had snowmobile and camping trailers with the 7" brakes for 39 years. They are nothing but trouble. One issue that has been the most frequent is the clip that holds the magnet comes off. While you would think that there is not enough room for the magnet to come off the post, they will. My solution was to silver solder the clip in place. To do this, place a large washer over the magnet to protect it, and push the magnet back exposing the clip.
I had adjusters where the teeth would just crumble and those parts are no longer sold separately. I made my own adjusters from stainless steel. Lube the threads with anti-seize.
I have tried brands other than Dexter, but had magnet wires break off first trip. There is no good answer that I have found. Over 30 years ago, the brake shoes had riveted linings and generally were made better. They worked well, but there was only 1/32 of lining above the rivets and needed replaced every time you looked at them.