Whenever I step onto my treadmill the belt stops right where it is and this ungodly scream/squeal/screech fills the room. I have tightened the walking belt, loosened and greased everything to no avail.

Could it be the motor belt does not have enough tension? Everything moves fine until I step up on the deck and then the belt and rollers stop and the screaming begins. Is there a way to increase the tension in the motor belt or do I have to buy a new one?

Thanks a million in advance for any advice

Get a refund.

I use to have a elliptical machine a long time ago that made that odd sound.

The drive belt from your motor to your front roller flywheel is loose. You need to have a professional tighten the belt or replace the belt. Its not a major problem, however you need a bit of technical knowledge about treadmills to do it yourself.

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The most common cause for the problem you describe is a loose/squeaky drive belt ( I used to service fitness equipment)

In addition to the other recommendation to tighten the belt - (it still may squeak when the tension is correct) you should rub a bar of soap on the inside of the drive belt. Alternately you can buy "belt dressing" spray at most automotive stores which is designed to increase traction, prolong the life of the belt and most importantly - eliminate squeaks.

If you are reasonably handy with tools, it should be very easy to tighten the motor - Make sure the unit is unplugged, pull off the top motor cover and look for an adjustment on the motor mount. If this is a bit over your head, any (reputable) specialty fitness store can send out a technician to do this for you.

Back in the 1990's the True Treadmills used to squeak until they went from steel to nylon pulleys on the roller...

Could also be your front roller. Sometimes the front roller separate from the flywheel pulley. This also causes slippage. It could be a combination of your walking belt, drive belt and front roller. If you're in NJ or NYC area give Techmotion a call.