Cleaning the rear brakes...

[Edmond]

How often do you have to clean the rear brakes? I mean, on full floating axles this is not an easy thing to do...
Why do I want to know you may wonder...Well since a few days I have this sound coming from one of the rear drums when I'm applying the brakes. It's this high whistleling sound.
After asking around they told me this was because there's dirt in there.
I have changed the brakes shoes two years ago, they can't be worn already?

Any one of you have any ideas?

Thanks in advance.

Cya,
Edmond