Why is my elliptical trainer noisy?

Or, Handy Maintenance & Service tips for Residential & Commercial Elliptical Trainers.

Elliptical service tips. 
"Help. My Elliptical trainer is knocking when I use it."
"My Elliptical trainer feels wobbly."
"My elliptical makes a whining or scraping noise."
These are the most common complaints/questions we get for elliptical type trainers and cross trainers.  Here's some useful info to help understand the reasons for these problems, and what we can do about it.  Repair your elliptical  yourself, or give us a call. We're happy to help.
Knock and Level:
Old elliptical trainers are noisy and usually have a knock, from a rotating arm inside the flywheel housing hitting the plastic housing.  This is caused by a few things:
   Ellipticals are not very rigid and are subject to a lot of torsional force (twisting around the center axis):  Aggravated in residential and commercial settings by being placed on a carpet; and not kept level or properly supported.  100% of older ellipticals knock (in my experience).
    If on a thick, plush carpet, can't really level.  Put a piece of 3/4" OSB under the machine.  We will do this for our for customers for $55 +tax and trip.
   If on a hard, level surface, then check the level of the machine, and adjust so that it is level.  MAKE SURE leveller feet are still there and still have the little rubber foot.
   The wear bushings in ellipticals wear out over time, and make the arms and limbs looser than original fit.  When this gets too bad, the foot platforms will actually start to rotate or pronate.  PARTS ARE CHEAP to replace, but is a lot of labor.

  Wear.
Ellipticals biggest wear items are the rollers for the left and right platforms.  They should be wiped clean before every use, but this rarely happens.  Dirt builds up and the wheels wear, spall, or chip unevenly.  This affects the ride, feel, and noise of the machine.  Inspect the wheels carefully on every machine.  Replacement is warranted for uneven wear on the wheel of any kind.

  The flywheel housing. 
This is difficult to get in to. Fasteners are hidden.  The rotating arms are very hard to remove, and it is hard to maneuver the plastic housing around.
CALL technical support if you need to take the housing completely off.
Use extra caution when the housing is off and still around the rotating arms.
disassemble as little as possible.
DON"T take it apart if you don't have the tools and personnel to put it back together.

Drive belt:
This is a wear item. It needs to be checked during a service.  Look for rubber spall or rubber bits inside the housing as a sign of wear.  Inspect the belt for dry rot, cracks, glazing, and splitting.  Check the inside grooves of the belt: grooves should be pronounced, not worn off, and not all filled up with gunk, dirt, and hair.  Replace if any of those conditions exist.

Frame assembly, uprights, console, arms:
These things are supposed to be checked and tightened on a routine basis, which does not get done in most cases.  The elliptical arms become loose and wobbly.  Check and tighten assembly points, which are usually hidden behind plastic body parts/shrouds.  Usually need metric allen wrenches or phillips drivers.

all for now.
 
That's it for now.  Go forth and don't break anything :)