Maytag Neptune TL - nd (will not drain code)

My Maytag Neptune TL has just started to code "nd" at 35 minuntes left in the cycle. It happened a few times, then was o.k., and now it’s happening again. Manual says to check for restricted drain system. If this is just the output tube on the washer, it’s o.k. Is there something else I need to check? Google produces a lot of matches that lead me to believe I need to replace the clutch, but those same matches also say to see if you can spin the empty tub freely with your finger - which I can. Does the spinning freely mean it’s not the clutch, or that if it spins with nothing in it and does not spin with the clothes in it, it is the clutch?

I’m running a quick wash (no clothes in the machine) to see if it will complete empty.

Perform the troubleshooting as described in the Service manual.

Here are the breakdown diagrams and http://www.appliancepartspros.com/partsearch/model.aspx?diagram_id=1350397&&model_id=5169371

Gene.