How to clean out brake fluid reservoir?

[atikovi]

I bought a 500E that was stored for the last 5 years and there is a coating of black crud on the inside of the brake fluid reservoir above the fluid level. Can I remove it from the master cylinder and clean it out with some bent wire or q-tips or does the reservoir have chambers that I won't be able to reach? Trying to save $50 and not buy a new one.