It doesn't really sound like there is anything making direct contact with anything else, really the sound seems like air being pushed through a tight space making something vibrate, like when you make a blade of grass into a whistle, or , well, a kazoo. Still, I'll certainly get in there and have a look around.

No it just needs oil.

Get a small 1/16 ID teflon tubing or similar and dangle it into the airbox from the front vents. Feed 3-in-1 oil or ATF down onto the bearings at the left and right sides of the box where the blower wheels are mounted to the shaft. It takes a long time to drip enough oil and get it where it needs to be. Wiggle the tube around until you hit the shaft and keep it there for an hour, it'll work it's way in.

My '91 245 started the Kazoo noise about 230k miles. I'm now at 340k miles and it's as quiet as a mouse. BTW, the noise can be the blower wheel against the housing, but that's much louder, and often jams and doesn't spin at that point, and then you will need a new motor w/bearings.

FYI, I drilled a hole in the airbox and mounted the tube permanently on a '78 242 GT which worked great, dripped the oil once a year or so, never went bad on me. In fact since I did my first airbox blower motor about 30 yrs ago, it was the last one I will ever do again, as this procedure makes the motors last as long as the car.

PS don't be tempted to spray WD-40 as it's not oil and will wash away any oil or grease left in the bearings and then dry up and really squeal.