I've always felt (but have no evidence) that positioning a yaw string on
the canopy is not optimal, and that you really want it in clean,
undisturbed, air (yeah, like the 2-33). There could be 2 problems with
the canopy mount. One, it is flush with a compound curve surface and who
knows that the air is doing there. Two, it is in the boundary layer
between the canopy surface and the airflow and who knows that the air is
doing there.

I wonder if any one has experimented with a "normally" mounted yaw
string and one placed on a post several cm higher.

Tony V.