To remove the spring lid handles stand to one side and grip one end of the spring with both hands. Pull towards you and bed slightly at the same time. As the spring compresses you'll be able to slip it off the 'nub' that it sits on. Keep your skin away from the very ends - believe you me it hurts if you don't quite get the spring off and it 'pops' back on trapping your skin!
To refit new spring handles stand to one side and place one end of the spring over one of the 'nubs' and cap. Pull the spring towards you and simultaneously bend the end towards the other nub until it can 'pop' on - again be careful of trapping skin!