The lead nut assembly consists of two components - coupling nut clamp and lead nut mount. Coupling nut clamp holds 1/4" coupling nut. Its position is adjustable relative to the lead nut mount. This allows to align the leadscrew to be parallel to the angle in one plane (side-to-side in the pictures). Once this is aligned and tightened, the lead nut mount with the coupling nut clamp is installed inside the sliding element. The lead nut mount position is also adjustable relative to the sliding element. This allows to align the leadscrew to be parallel to the angle in the plane perpendicular to the first one (up-down in the pictures). The result is that the leadscrew is parallel to the angle.
Note that before attaching coupling nut clamp to lead nut mount, two 3/8" long screws are installed in the lead nut mount. They will be used to attach the lead nut assembly to the sliding element. To insert the assembly into the sliding element, two UHMWPE pads may need to be removed.