41B & 42B Brass Leadscrew Nuts - Assembly Tips
Misunderstanding how the lead nuts are supposed to work on a Lucas leads to early nut failure.
If this applies to you, you will notice that the threads are almost completely worn out inside the fixed nut, while the threads inside the adjustable nut look almost new.
Adjusting Lead Nut Backlash
CAUTION: Do not set the backlash too tightly on a worn section of the screw. The nuts are very likely to jam if the machine is traversed to a place on the screw where only slight wear has occurred.
When replacing nuts on a used leadscrew, be certain to examine the screw threads for damage, wire edging, and general wear which could result in the screw seizing in the new nuts or cause them to become prematurely worn.