My ski ran great for the first half of the summer. I went away for three weeks. I came back the ski started, I ran it for about half a mile. I hit a wake, the ski seemed to bog down and lose power then it died. I went to start it and the battery was dead. I noticed the wire had come undone. I got towed back to the dock and tried jumping it and it would turn over fine but not fire except for once or twice. I charged to batteries. Went back to the lake and tried it. Cranked a few times but seemed like the battery was week. It did this with both batteries. I have cranked it numerous times before and it never killed the battery that fast. So I hooked up a jump box and it cranked but would not start. It has gas getting to it, spark at the plugs. I noticed the injector oil hose was cracked so I fixed that. My buddy hooked up the vacuum gauge to it and said there was hardly any compression in the cyllinder closest to the rear of the machine. Will a blown head gasket cause these problems and only in one cyllinder. I really want to ride my jetski so if anyone has any ideas I would appreciate it.