Have you a voltmeter handy to check battery voltage at rest & when trying to crank?
Take the terminals apart and wire brush them....Not sure how I could go about cleaning them though?
Boil some water, or just get some really really hot water from the sink and pour it over the terminals to clean them. You can use a small brush if needed but the hot water should take care of a little gunk that builds up.I am nowhere near confident enough in my abilities to take apart battery terminals and clean them myself... I'll find someone willing to do it for me Thanks for the help though.