I have not been able to find a rebuild kit such as the ones made for the upright Williams games.
What is the best way to make sure I get the correct length leaf to replace these?
Like I mentioned above, arcadeshop should have the correct leafs, they used to have the mechanical parts/pivots for the cocktails as well, email or call and ask.
I'm sure you can match leafs up by length at a number of pinball parts suppliers.
As to comments about some other problem causing your non-functional stick, there are numerous things that can cause this, but these machines tend to be riddled with connection issues. I would start by going over the widget board connections. Sometimes just reseating the connectors can clear things up.
D