Mine used to make noise till I changed out the old powersteering fluid and filled it with syn. trans. fluid (Mobil 1)
It's been quiet now for many years, might be worth a try.
1) I used a turkey baster to remove the old fluid from the resevoir
2) Then hit key to refill the resevoir somewhat, then re-empty resevoir a few times until no more fluid is pumped back in.
3) Then fill with the syn. trans fluid until full again.
Nothing to take apart this way.