I just had one of mine apart this week, I had good, firm pedal, but almost no braking action. I ordered all of the seals and had them ready, and when I got it apart, both linings had come un-bonded off of the shoes. Also, the cam was seized in the bore, and the dead end of both shoes were seized on their anchor pins. I cleaned it, freed it up, lubed everything sparingly, and was able to get a set of shoes. Works good, now. One un-expected glitch was the seal on the outer end of the dust cover had worn deep grooves in the wear sleeve on the hub. Fortunately, it is a relatively inexpensive wear sleeve, instead of a pricy hub. Unfortunately, the sleeve had to be ordered, so I will have to go in to it once again when the sleeve gets here.
Don't hesitate to dive into this job, it is not that tough. And, it should probably be serviced (cleaned, checked, lubed) a couple of times per year, more if you like riding underwater.