Sorry its taken so long to let you know how the idea went with the pen spring, to many projects and winter is here so time in the workshop is limited body just isn't what it used to be.
Well the result was great
except that the normal length pen spring needs to be cut down by 1/3 or a deep hole drilled in both parts.
If the spring is left to long the head will bob to much and weight will stop the clown from dropping as its counter productive in force.
I left about 1/4" gap between body and spring which seems best, if you leave it less or spring seems to tight no bobbing then just elongate the spring.
I'll post a photo or 2 when LOML has painted them both.
Ray