Need some advice troubleshooting my starting system. I have a o320 150 hp which was installed when I build my RV7A and finished in 2009. Rebuilt by Stein. I has started fine with only some hard starting when hot. Within the last three or four months it has been more difficult to start. The battery is six years old (Odyessy 680) and I installed new spark plugs 8 months ago. The skytec starter turns the prop great, but it usually takes several seconds and several trys before the engine with fire. Have checked magnetos, they were overhauled last summer. Any and all suggestions would be greatly appreciated. Thanks