nordic track a2350

So far we've been disappointed in quality and service. After the product arrived missing a part we called with model and serial #, etc. We were told to fax a copy of the sales receipt and a file would be opened for us. This was done and we received confirmation of the file but have yet to receive said part (10 weeks so far). While the part is important (speed down button) we have been able to use the treadmill without it. Now the belt is slipping and has begun sliding to the left against the side rail so that the machine is unusable. Any attempts at adjustments according to the manual have been unsuccessful. I called the help line at 530pm Atlantic (it is advertised as being open until 5pm ET) and had to leave a message on voice mail. We had a considerably less expensive treadmill previously that provided hundreds of miles of runs.