Blower and Battery Questions

The skiddim FAQ has an interesting way to test for a drain on the battery using a test light:
http://www.skidim.com/Faq_TROUBLESHOOT.asp#who

I'd also test, using their method, both with and without your radio connected.

Hello Friends,

Boat - ISki Nautique 19.6 -1998 GT40

Question #1
Blower is very noisy whiny and loud and cuts off after running for only a short period. Does anyone have any tips on the following:
- where the unit is located on the boat
-tips for replacement
-where i can find a new one

Question #2
Battery died on me while skiing this weekend. Boat seemed to be running fine for several hours. I did notice that the volts on the dash gauge seemed low around 9 - 10 but boat was cruising along fine. After several starts and stops of teaching a new kiddo how to ski. Boat died and battery was dead cold. Threw the battery on a charger and it was dead but charged back up quickly (an hour or 2). Battery is an Interstate that is probably only 1. yr and a half old or so. Do you think it is most likely the alternator or loose alternator belts?

On a side note i did just replace the radio. The radio was replaced once before by the previous owner. I noticed that their was an additional ground wire (different from the red, black, blue, red, and white wires from the radio harness) that was grounded to a screw on the metal radio housing? Is that something that is standard with these boats? I just reconnected it to the new radio housing. Could that be the source of the problem.

Thanks Nautique Community