A 1988-vintage Cobra probably has replaceable bearings. They can be
found at large bearing supply houses in the U.S. The numbers are
stamped on the races of the inner and outer bearings. You'll need
grease seals for the inner bearings, too, which can be more difficult
to find for older trailers. The bearing supplier I used had grease
seals that fit perfectly for the axle on my 1992 Cobra.

Later Cobras apparently have sealed-for-life bearings that are pressed
into the drums. At least one guy reported replacing these bearings but
the standard fix seems to be replacing the entire drum assembly.

People have had problems with brake drums before, usually small cracks
in the hub. As far as I know, replacement is the only option (though I
have considered turning the hub down and slipping a steel sleeve over
it to take the stress off the crack, then sealing the crack to prevent
grease from seeping out of the hub).

Have you tried Tim Mara at Wings & Wheels? He usually has drums,
bearings, and brake shoes for various Cobra and Komet models.

The alternative is a complete axle replacement but Alko seems to be the
only company offering a mechanical surge brake. Using a U.S. axle will
mean losing the surge brake (and handbrake feature) or substituting a
hydraulic surge brake or electric brake assembly.

Chip Bearden