I do not have experience but I have an article on how to do this. The instructions are very terse so use it at your own risk. Email me and I will email you a PDF.
If your rangefinder appears to need cleaning. It might be the case that the silver coating on the prism in the rangefinder is flaking off. This gives the appearance that your rangefinder in dusty. I have lived with this problem for years, but the amount of 'dust' in my case is minor.
