If the spindle taper didn't catch the holder from it's stud then you need us for the spindle solution.
ANS:
1) Holder will not get clamped in the spindle taper.
2) Spindle did not release the holder.
3) Holder can suddently declamped during running which can cause serious accident.
Clamping of holder is responsible for the holding the holder stud in the fingers of the draw bar.
Draw bar consisted of special wave washers or spring, aligned in a specific manner which creates the pull for the holder stud. Draw bar design is of two types, first which is made of fingures and second in which balls are used to hold the stud of the holder.