Hi, thank you for contacting JustAnswer.com. My name is Russell. I feel that your question deserves an answer, though you have evidently found a solution elsewhere.
If the assembly instructions were all followed to the letter, but the machine never fit together properly and never stayed together, then you have a machine that was defective from the store. Unless it was sold 'Used' or 'As-is', you should pack it up and return it promptly to the store, for an exchange for another machine in working condition, of that type or of equivalent value to you... or for a refund.
Do so ASAP for the return-exchange period runs out very soon, if it hasn't run out already.
If the return-exchange period has already run out, then the maker (NordicTrack) should honor their warranty on the machine if contacted fairly soon about the matter.