The square tooth screw and nut tend to fill with sawdust, which saturates with oil to cause the threads to bind (like a dirty nut and bolt.).
Clean the bolt with a cleaner, then apply a little wax to the threads (crayon or bees wax). Be sure to run the assembly up and down to cover the whole "bolt" and make sure to apply to the point of the screw that assures some of the wax works into the nut.
Wax is less likely to cause wood dust "mud" that WD-40 or other lubricants would cause.
Check the slides or guides that guide the assembly as well. CLean and lubricate with wax as needed.
Answers & Comments
The square tooth screw and nut tend to fill with sawdust, which saturates with oil to cause the threads to bind (like a dirty nut and bolt.).
Clean the bolt with a cleaner, then apply a little wax to the threads (crayon or bees wax). Be sure to run the assembly up and down to cover the whole "bolt" and make sure to apply to the point of the screw that assures some of the wax works into the nut.
Wax is less likely to cause wood dust "mud" that WD-40 or other lubricants would cause.
Check the slides or guides that guide the assembly as well. CLean and lubricate with wax as needed.
Let me know what you find out.