I got back a week ago, only to find that my
Dad's 11x26 lathe was leaking oil from the
gearbox. Finally got around to pulling the gearbox
cover off (and the 1/4 inch of oil left promptly
came out) and saw the problem is due to the 1/8th
inch bead of hard sealant that the manufacturer
used. It finally failed on the bottom edge...

FWIW, you can leave both gear change knobs on
the cover instead of punching out the roll pins.
Keeps the detent balls and the springs in place...

If your gearbox is leaking, and the four
mounting bolts are tight, suspect that the factory
sealant failed.

What you need to fix it:
Phillips head screwdriver to remove aluminum
speed/feed chart
Roll of absorbent paper towels (about 1/4 cup of
oil left inside!)
5mm hex wrench
Permatex (I chose Type 2 for a resilient gasket)

Arrange paper towels under gearbox. Take out the
four (5mm) cover bolts. Pull cover straight off.

The cheap bead of sealant is on the reverse of the
cover plate, which makes it easy to use a scraper
to remove the old bead. Clean off mating surfaces,
using a degreaser. Apply Permatex according to
directions. Re-assemble.

If you have changed the position of the knobs, one
way to orient the swivelling gear change guides is
so that the sliding gear is on the middle fixed
gear. Set the gear change knobs so they are for
the middle position.