FYI...

The Cobra trailer for one of the two CAP ASK-21's had developed a
problem with the left tire and had a tendency to sway. The tire was
deteriorating rapidly, wearing on one side with severe cupping. The
tires were relatively new trailer rated bias ply. Theories ranged
from a bent axle to a bad tire with misaligned belting.

A trip to a professional trailer shop uncovered the real cause -
jammed left brake. The Cobra's surge brakes are purely mechanical
with a push-pull rod from the hitch to near the axle where two cables
run to the drum brakes. The left cable had become jammed with dirt
and wasn't releasing the brake causing it to drag until it could
barely roll. The asymmetrical braking was contributing to the
swaying.

There are no dust boots on the cable housing to keep dirt out so this
is likely to be a recurring problem.

All the towing vehicles have electric brake controllers installed so
I'm campaigning for converting the Cobra trailers to electric brakes.