DirtyHarry,
I got my new brake lever from the place I bought my 4 wheeler, Parkside Marine in Brookville, Indiana. The guy I talked to said that AC was having alot of trouble with the plastic one breaking, so I believe all the new ones have the aluminum replacement. Haven't had any trouble since. Oh yeah, I think AC knows they're breaking, because mine run me about $20. If you can't find one, let me know and I'll try to track one down around here for ya!!
--longshot--