how do i check if the coil is working?

i think i have droped a coil or plug.

how do i check if im getting a spark?

please help need to fix it but dont want to have to spend money on parts i dont need.

also on the coil for the front spark the metal bits that attach it to the frame are rusty. should thay be?

[flymo]

You can test a coil/plug in one go. Remove the plug from the engine, connect it to its HT lead and ground the plug thread to either the engine casing or some part of the frame. Keep it well away from the spark plug hole it came out of or there's a danger that you'll ignite any fuel vapour that gets forced out.

Give it a quick burst on the starter button and you should see a good healthy spark.

The metal bit that mounts to the frame may show signs of corrosion but the join to the frame needs to be clean in order for it to earth properly. Give them a good clean with a wire brush and refit.