If you need to replace the gauge, the only current option is a Faria guage from NautiqeParts.com (or others). It's basically the same thing, but it uses post connectors instead of spade connectors, so you'll have to do a little minor wiring.
But, the temp gauge operates on variable resistance to ground. I believe a peg to the right could mean that it's finding a direct path to ground.
Check out Skidim's Faq's: Look at both OVERHEATING and WATER TEMP SENDER:http://www.skidim.com/Faq_TROUBLESHOOT.asp
It could also be the sender that is the issue.