Master cylinder leaked fluid onto the alternator and now the alternator is not working

Well you have nothing to lose.

A new alternator may be the last resort.

The damage may already have occurred.

I drive Jeeps, 1970's type and on back.

I do not know what kind of electronics might be in yours.

Many, Many, Many times I have been out in mud/ mud holes/ even a pond or two. I have submerged my engine quite a few times in water. That would include the alternator too! I have never had a problem with it getting soaked.

Which brings me to maybe your last ditch effort before you buy a new one.

Remove the alternator and submerge it in a bucket of water. (Doing this on the vehicle may mess up other electronic stuff)

Brake fluid is water soluble. If you ever spill any, the garden hose will wisp it away leaving no trace or residue.

Shake it around in the bucket, even rinse it in a fresh bucket of water.

Remove from the water.

Let it drip dry, or even use a compressed air nozzle to speed it up.

I recommend in your situation you let it dry a long time, maybe changing it is position from time to time.

I hope this keeps you from buying a new one.

Let us know how it goes.

The Medic