I remember an instructor and student getting into trouble trying to recover from a spin in a T67 in the UK.
Its a few years ago but when the Instructor told me what happened I could see how a student could get themselves into serious trouble. Thankfully both student and instructor survived the incident.
To the best of my fragile memory.
The instructor demonstrated a spin and recovery with no problems.
Handed control to student, the spin and recovery was normal until the "pull out from ensuing dive" part, they started to pull out of the dive but suddenly and violently departed and flicked hard into another spin.
The instructor took control and initiated recovery, once again the recovery was normal but in the later stages the aircraft once again flicked into another spin.
The instructor thought the problem was they were pulling too hard during the recovery causing the pitch angle to increase rapidly causing a further stall spin. On the last attempt he was much gentler in the recovery from the dive. The aircraft recovered normally.
Now if this had been a low houred pilot watching the ground getting ever closer and with a certain amount of panic setting in I think it would have ended in disaster.
Its the only first hand account I have come accross and it seems to fit the other failure to recover stories I have heard.
It certainly cured me of wanting to spin a T67.