From GASIL 7of 2012 : We have been made aware of an incident which occurred to an instructor and student carrying out practice forced landing training in a Cessna 152 earlier this year. Having trimmed the aircraft to the airspeed for best glide during the exercise, when the instructor demonstrated the go-around from the approach he found it impossible to move the trim wheel again. Apparently a broken nylon bush had allowed the trim wheel to come off the spindle in flight. The pre-flight check had identified nothing abnormal with the trim
Returning to base with the trim set for glide was tiring, but sharing the effort to hold the force apparently rendered it manageable. However, being aware of the trim changes required with flaps set, the instructor opted to make a flapless approach to an into-wind runway. As the instructor notes, while a trim failure may not seem a particularly major problem if it happens in cruise flight, when the seizure occurs at one extremity of its travel it affect the handling considerably!
Reference : GASIL 7 of 2012