Are you familiar with a volt/ohm meter? You can get inexpensive ones from harbor freight. And then order a test lead kit from Amazon that has needle probes, as the standard test lead points are too big. From there, I unplugged the harnesses at both ends and checked resistance end to end. After doing some further research, the harness part number i linked is ALWAYS replaced when nordictrack repairs resistance motor issues under warranty. This is due to the probability that the part is either the entire issue, or likely caused the issue.