its been like 2 months that my rear whipper has be stalling like studdering/ jerking on whipping my hatch window. is my motor dead, is the screw to tight? can my fellows rx7 brothers help the kid out thanks. if it helps i have a 87 turbo

 

Raise the wiper (or "whipper", if you prefer) arm so the blade isn't on the glass and run it.
If the action is still jerky, then your motor is probably going bad.

I don't think you can actually overtighten the arm retaining nut but I could be wrong about that.
At any rate, loosen it a turn or two and see what happens.

Check the electrical connections at the motor.