Every once in a while but not always the VUK (vertical up kicker) on on my Party Zone will keep kicking the ball up and not quite make it and keep trying. Only happens occasionally, always when my wife is having a good game. Wondering if I need to resleeve the shaft or should I be looking at something else. I noticed that the kicker shaft does move freely when I slide it by hand. The coil doesnt show any sign of being burnt.

Any ideas how to strengthen it? What steps to take?

Quoted from wbradley

Every once in a while, but not always my Party Zone will keep kicking the ball up and not quite make it and keep trying. Only happens occasionally, always when my wife is having a good game. Wondering if I need to resleeve the shaft or should I be looking at something else. I noticed that the kicker shaft does move freely when I slide it by hand.
Any ideas how to strengthen it?

Wish I knew how to help your VUK but I originally read your message  the way I have it edited.  Must be my dirty mind.  

Re-sleeve it and clean everything, check your wiring to make sure you have good connections. You can check to make sure you've got the correct voltage at the coil, but if you aren't able to get enough current through a bad connection, you may have the correct voltage there and still not fire the coil strong enough.

Is the problem a weak kick or something obstructing the exit?

will inspect closer, including connection, voltage etc clean and only resleeve after if this doesnt work.

thanks

Sounds to me more like there is a misalignment rather then a problem with the coil, it's most likely hitting on something it shouldn't be when kicking it up stopping it from getting the power it needs to get all the way around.