I own a bicycle shop and we use cable lube on all tune
ups. When a cable goes over a pulley or through housing,
there is friction and wear. The original rudder cables
off my Libelle (replaced) were braided over hemp rope.
This reduces internal friction and holds lube. Lubing
the cable will make a big difference on the brakes
and rudder. You can get wax type lubes that don't pick
up and hold grit, as grit on the cables can cause wear
also. Cable lube will prevent internal corrosion which
causes wear and lots of friction. On older gliders
the brake cable is a moped or bicycle cable. Replace
the cable and housing with a modern coated cable with
teflon lined housing. Prelube the cable before installing
and you will get much more stopping power to the wheel.