Hi there -
If it's the original from the '74, it's probably ready for replacing... but I'm providing you a link to troubleshooting the water heater just in case:
http://www.ducktec.com/waterheater-trouble-shooting.html
After some searching, I was able to find two great online guides for you that will walk you through each step of replacing it, with pictures:
http://rvtravel.com/blog/rvnow/2007/02/rv-water-heater-replacement.html
http://www.diynetwork.com/diy/ab_trailers/article/0,2021,DIY_13699_4855735,00.html
Once you have your new unit in, here are some tips to help extend the life of it:
http://www.rverscorner.com/rvwaterheater2.html
If this is helpful, please click Accept as it's the only way I will receive credit for my effort.
Thanks,
Dave
