I have a probably 13 yr old water heater, so I know its getting up there. I just got a leak on what looks to be the hot water outlet. (The leak is hot). It doesnt look to be the joint, and it seems to be coming from under the cover/red cap. I found some threads talking about dielectric nipples. Could replacing or tightening these help? What should I do to further diagnose without causong a problem getting things back together if thats not it considering the age of the heater? I included a pic if that helps.