97 Seadoo GTX Battery/Starter issues?

[Pieman]

Every year I seem to have problems with my Seadoo maintaining battery strength. It almost seems like something is draining its power but nothing is on. I just worked on getting it ready for the season last night and the battery is fully charged but when I attempt to start it, it doesn't crank - it just has a week skipping sound. I put a charger on the battery and wiggled the cables and got it to start once and it ran until I turned it off. Then immediately tried to start it again and it would not even crank. Does this appear to be a problem with the battery cables?