alu-idler for rusty ?

[OldSoldier]

Guys,
I have the same Idler gear question for the E-Maxx. I have a Feigao 9L motor, Quark 80B controller, and I run 14.8v (two 7.4V Lipo batteries). I'm being careful with it for now because I don't want to break anything. Four questions:

1) What are the first symptoms that the idler gear is getting ready to break?

2) I'm starting to hear a momentary click somewhere in the drivetrain when the drag brake kicks in when I let off the throttle... Is that likely to be the idler gear?

3) I looked for a metal idler gear a week or so ago online and I could not find anyone who had them in stock. Anybody know where I can get one for an E-Maxx?

4) Are there any other gears in the transmission that need to be replaced?

OldSoldier