Ensure the snowblower engine is cut off. Find the spark plug on the top of the engine block. Pull the thin, black ignition wire out from the rear of the Toro's spark plug as a safety precaution.
Remove the Toro snow blower's cover by loosening and removing the screws that secure it. You can remove these screws with a Phillips screwdriver.
Remove the screws immediately surrounding the primer's rubber cover with your Phillips screwdriver. These are the screws that secure the cover in place. Pull off the cover once these screws have been removed.
Position the new, replacement primer cover into place where the former cover previously resided. Insert the screws around the cover to secure it.
Set the snow blower's cover back into place and re-insert its screws. Reconnect the ignition wire into the rear of the spark plug.