Just to address the reference to the JS1 accident, according to
Uys Jonker speaking at the BGA conference, what happened
there was not a broken rudder cable but similar to what you
describe in the Janus (and various other gliders) i.e. a situation
of a high pedal force required to overcome a locked-over rudder
in a side slip.

This scenario is described in the JS1 flight manual as:

"WARNING: If an excessive slip angle is not corrected with
opposite rudder input, the secondary effect of yaw may cause
the sailplane to roll and enter a spiral dive. It is not possible to
prevent roll by applying full opposite aileron during excessive
sideslip.

CAUTION: The rudder control input force to recover from a side
slip exceeding 20° is high (approximately 20daN) and increases
if the speed is allowed to build up during the resulting spiral
dive. Apply sufficient rudder input to recover from the sideslip to
prevent spiral dive."

John Galloway

At 07:45 30 August 2013, Uncle Fuzzy wrote:
For fun. If you get the chance to fly a Janus up high. Play
with slips.
I=
t will 'lock over' to either side, dropping like a set of car keys
(Thanks
=
for that image JS) and the canopy mounted yaw string (s) will
be
pointing..=
... well, you'll see.
I started playing with this about the time that Jonkers broke a
rudder
cabl=
e and the guy had to bail. Having read Derek Piggot's warning
about the
Jan=
us, and realizing it really took a LOT of pedal force to
straighten up, I
s=
tarted thinking about 'recovery' if one of my 30+ year old
rudder cables
br=
oke. Turns out it IS recoverable, but involves a lot of elevator,
and eats
=
a lot of altitude. From a mile AGL, it's doable.=20

Wondering how long my wandering will persist.