This came from a manual that can be found online. Your tongue jack would be similar.
LUBRICATION
The jack is lubricated before leaving the factory. Under normal conditions, lubrication will be needed after one year. WARNING: The weight of the Trailer tongue should be supported by blocks or the Ball Hitch of the tow vehicle before proceeding.
1. The Foot should be fully extended.
2. Using the Toggle Switch, extend the jack until the Foot Pad is 2" from the ground.
3. Loosen the four #8 Phillips Head Screws and remove the Gear Housing Cover.
4. If required, repack the exposed gears with a common Lithium Base Machine Grease.
5. Reassemble Gear Housing Cover.
6. Using a 1/4" Allen Wrench, remove the four 5/16" Socket Head Screws holding the Motor Head to the Outer Tube.
7. Lift the Motor Head and Screw Assembly away from the Outer Tube.
8. Clean and regrease the Jack Screw and Nut with a common Lithium Base Machine Grease.
9 . Reassemble Motor Head and Screw Assembly to Outer Tube. Replace the Fuse.
