Nordic track elite 1300 elliptical makes a thumping noise and feels like it's missing
Make: Nordic Track
Model: Elite 1300
took it apart and tightened some fittings. re-greased it.
It can be the belt is slipping. The thumping usually occurs around the steel plates where the wheels run. They tend to crack. Here is a link to get parts and see an exploded drawing.
The belt slipping I suppose is a possibility. I'll have to open it up again and see if I see that. I didn't last time. All the "action" is on the left side assembly. There is a squeaking noise at the center axle, around the arm assembly. The "thumping", like there's a flat spot on the plate occurs at a precise location every time. It's been very tough to spot and it makes using the machine uncomfortable.
The axle has been replaced 1 time already, when it broke a couple years ago.
Check the belt, but also check the wheels for a flat spit.
It's not the belt.
I believe there is a snap ring on the long shaft of the axle. You may need to install a thin metal washer behind the snap ring in order to prevent the axle from having play and thumping. Also tighten the crank arms #83 on both sides, make sure they are pushed into the correct position against the spacers.
20+ years experience repairing exercise equipment with emphasis on Nordictrack/Proform and Horizon