STIHL Grass Trimmer FS450

Check electrode gap (A) and readjust if necessary

Rectify the problems which have caused fouling of the spark plug

Does the spark plug come with a detachable adapter nut?

Screw the adapter onto the thread and tighten it down firmly to reduce the risk of arcing and fire

Carefully remove the rope rotor with washer (3) and pawl (4)

Did the rewind spring pop out and uncoil during this operation?

Pry the cap (5) out of the grip

Remove the remaining rope from the rotor and starter grip

Tie a simple overhand knot in the new rope and thread it through the top of the grip and the rope bushing (6)

Ensure you have STIHL gear lubricant for brushcutters

Gather necessary tools: filler plug wrench, lubricant tube

Is grease visible on the inside of the filler plug?

Amount of grease to be added (up to 5g)

Screw the tube of lubricant into the filler hole

Squeeze lubricant into the gearbox

Wear face protection and work gloves

Remove the rope rotor as described in 'Replacing the Starter Rope'

Remove the spring housing and pieces of spring

Lubricate the new replacement spring with resin-free oil

Place the replacement spring with spring housing in position, bottom plate facing up

Check for noticeable loss of engine power

Clean the area around the filter and inside the filter cover

Remove and inspect the filter element (3)

Is the filter element dirty or damaged?

Replace the filter element if dirty or damaged

Install the filter element in the filter cover