Unable to fold the treadmill. The latch knob doesn't "hold" the treadmill.

try pushing upon the deck to relieve the pressure on the latch. then pull the knob

PuPush up on the fold-up portion then pull.

HOW TO FOLD THE TREADMILL FOR STORAGEBefore folding the treadmill, adjust the incline to the lowest position. If this is not done, the treadmill may become permanently damaged. Remove the key and unplugthe power cord. CAUTION: You must be able to safely lift45 pounds (20 kg) to raise, lower, or move the treadmill. 1. Hold the metal frame firmly in the location shown bythe arrow at the right. CAUTION: To decrease the possibility of injury, do not lift the frame by the plastic footrails. To raise the frame, bend your legs, keep yourback straight, and lift with your legs. Raise the frameabout halfway to the vertical position. 2. Raise the frame until the latch knob locks into the storageposition. Make sure that the latch knob is locked in thestorage position.To protect the floor or carpet from damage, place amat under the treadmill. Keep the treadmill out of direct sunlight. Do not leave the treadmill in the storage
position in temperatures above 85 Fahrenheit.

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1. Hold the upper end of the treadmill with your right hand
as shown. Using your left hand, pull the latch knob to the
left and hold it. Pivot the treadmill down until the frame is
past the latch pin. Slowly release the latch knob

I will strong that you see your owner manual. If you do not have manual.
here is the web page for you download free right now:

http://www.iconservice.com/CustomerService/manualsProductManuals.do?model=EPTL88105&modelName=EPIC+425+MX+

sincerely.Good luck.

The fold up latch is on the underside of the walking surface. There is a chrome tube that has a pull knob on the side of it to release the treadmill and allow you to fold it down. You do need to lift the weight of the deck slightly to allow the pin to work freely. Once the pin is pulled you can ease the walking surface down flat.
Hope this helps.

Before folding the treadmill, adjust the incline to the lowest position. If you do not do this, you may damage the treadmill when you fold it. Remove the key and unplug the power cord. CAUTION: You must be able to safely lift 45 lbs. (20 kg) to raise, lower, or move the treadmill.
Hold the metal frame firmly in the location shown by the arrow at the right. CAUTION: To decrease the possibility of injury, do not lift the frame by the plastic foot rails. Make sure to bend your legs and keep your back straight as you raise the frame. Raise the frame about halfway to the vertical position.
Raise the frame until the latch knob locks into the storage position. Make sure that the latch knob is locked in the storage position. To protect the floor or carpet from damage, place a mat under the treadmill. Keep the treadmill out of direct sunlight. Do not leave the treadmill in the storage position in temperatures above 85° F (30° C).
To lower follow this procedure:
Hold the upper end of the treadmill with your right hand. Pull the latch knob to the left and hold it. It may be necessary to push the frame forward as you pull the knob to the left. Pivot the frame downward and release the latch knob.
Hold the metal frame firmly with both hands and lower it to the floor. CAUTION: Do not grip only the plastic foot rails or drop the frame to the floor. Bend your legs and keep your back straight.

Make sure the incline is at its lowest point 1. Hold the treadmill with your hands on each side of the frame at back of treadmill To decrease the possibility of injury, bend your legs and keep your back straight. As you raise the treadmill, make sure to lift with your legs rather than your back. Raise the treadmill about halfway to the vertical position. 2. Move your right hand to hold the treadmill firmly in the upright position. Using your left hand, pull the latch knob to the left and hold it. Raise the treadmill until the latch pin is aligned with the hole in the catch. Insert the latch pin into the catch. Make sure that the latch pin is fully inserted into the catch.

Before folding the treadmill, adjust the incline to the lowest position. If you do not do this, you may damage the treadmill when you fold it. Remove the key and unplug the power cord. CAUTION: You must be able to safely lift 45lbs. (20 kg) to raise, lower, or move the treadmill.Raise the frame until the latch knob locks into the storage
position. Make sure that the latch knob is locked in the storage position.

1. Hold the upper end of the treadmill with your left hand. Pull the latch knob to the left and hold it. Pivot the frame downward and release the latch knob. Note: To release the latch knob, it may be necessary to push the
frame forward as you pull the latch knob to the left.
2. Hold the metal frame firmly with both hands, and lower it to the floor. CAUTION: To decrease the possibility of injury, do not lower the frame by gripping only the plastic foot rails. Do not drop the frame to the floor. Make sure to bend your legs and keep your back straight.

From the owners manual:

HOW TO LOWER THE TREADMILL FOR USE

1. Hold the upper end of the treadmill with your right hand.
Pull the latch knob to the left and hold it. It may be necessary
to push the frame forward as you pull the knob to
the left. Pivot the frame downward and release the latch
knob.

2. Hold the metal frame firmly with both hands and lower
it to the floor. CAUTION: Do not grip only the plastic
foot rails or drop the frame to the floor. Bend your legs
and keep your back straight.