Usually the ProFile's "jet-engine" noise can be nearly eliminated by adjusting the static brush.
The static brush touches the bottom end of the spindle axle, and after some period of wear, can vibrate quite loudly.
If you (carefully) remove the hard disk assembly from the ProFile chassis, and remove the circuit board on the bottom, you will see the static brush. A small tweak sideways is usually all that is required to change the point of contact and stop the excessive noise.
Make sure that the brush is still making contact with the axle so that it can do its job, and do NOT "lubricate" the point of contact.
Source: James MacPhail / LisaList 2005.09.07
I've got 4 profiles. Of these 3 make the fridge compressor noise. They've all been alive for over 20 years now and still work. Granted, I rarely turn any of them on, and even then, only for a few hours, but they still work.
The Larry Pina book, Macintosh Hardware Repair Secrets describes how to fix this. It's a bit of a rare book to find, and usually around $30-$40, but it's worth getting. Chapter 13 of this book is what you're after:
"Some hard drives tend to be intermittently noisy, likely an annoying loud refrigerator... The fix is to remove the drive and check for a static discharge button. Intermittent strange noises often mean the discharge piece is too close to the media. Bend it back with a soldering aid as shown in figure 13-29 and the noise will be gone. Be careful when you're doing this... Generally, all you have to do is bend it back a little."(The figure shows a soldering tool (the usual one with a blade on one end and a hook on the other you used to be able to find at Radio Shack) pointing to a circular knob in the middle of the board on the bottom of the hard drive.) It looks a bit like a spiral and is next to a crystal, a chip that has two large resistors under it, and below a large chip with a sticker on it. You can probably use long, a small head flat screwdriver instead.
I've not done this before, nor have I bent back the profile discharge tab - I don't mind the noise since I rarely turn the drives on.
Source: Ray Arachelian / LisaList 2006.05.11
Source: Simon Claessen / LisaList 2006.05.12
NOTE: It's generally not a good idea to run a hard drive upside down, this may cause damage as the drive heads scratch into the surfaces of the platters. NEVER MOVE A HARD DRIVE THAT IS POWERED ON! Power it off first, wait until the platters stop spinning before repositioning it[LisaFAQ] > [Hardware] > [Hard Drives] > [ProFile External Hard Drives] (Comment on this answer)