With the rail still on the absorbent paper towels, carefully and slowly move the carriage from one end of the rail to the other

The carriage should move smoothly over the entire length of the rail

Small changes in resistance are normal, but the carriage becoming much harder to push, or binding completely are not

Repeat the previous test whilst applying a small amount of force downwards on the carriage

The carriage will likely travel more smoothly when applying a downwards force, this is normal

If the carriage does not move smoothly, or binds completely, refer to the Linear Rail Troubleshooting Guide