At both dealerships I worked at, they required the technician to remove the resevoir and replace the grommets that seal the resevoir to the master cyllinder.

With the resevoir removed, plug the bottom holes with your fingers and fill with clean brake fluid a couple times and shake it up alot to break up any debris, and do that repeatedly till clean.

You can also run the revoir under hot water for a while to remove all residue, and it will look as good as new afterwards, just be sure to blow all the water out with compressed air before reinstalling.

Then we replace the grommets and put the resevoir back on.

The refill with brake fluid.

I always pump up my pressure bleeder to 15 psi not 20 as I have seen resevoir grommets pop and leak at the resevoir at 20 psi.
This is also a good reason to replace the grommets prior to applying pressure.

Also lay a towel on top of the unit and resevoir when pressure is applied in case a hose pops oss the bleeder or a grommet leaks so brake fluid does not get all over the paint and glass if there is a blowout.

I5 psi is plenty pressure to pump out the old stuff.

I always start at the wheel furthest from the master cyllinder and work my way forward.

Then I do them all a second time for good measure.

Always pump up brake pedal prior to driving off into the sunset after this repair, and check for leaks immediately after the test drive.

Keep in mind ,this job can turn into a nightmare on some of the older 107 cars and 126 cars.

I've seen master cyllinder seals blow out, brake caliper hoses plugged up, and caliper piston seals leak during this process, that is another reason to go with 15 psi.