Hi,
Does the scope show the PWM output of the ATtiny85 being adjusted by the pot?
What does the scope see on the drain of the MOSFET.
Is the damper/shocker an inductive load?
Can you post link to specs/data of the damper?
What is the supply voltage to the damper and is its gnd connected to the ATtiny85 gnd.
Please post a complete circuit including power supplies.
Can you post your code please?
Tom... 
