I noticed on my St Croix rod that one of the eyes is broke off, it is the third one from the top.  How difficult is it to repair myself and how would I go about doing it?

This isn't something that you learn by reading an article on it, and there surly isn't enough room to explain it all here.

It takes a lot of practice to get a guide replaced and wrapped the right way.

YOU should return the rod to the mfg. and have them do the work. Or find a local rod builder and have it done.

Just my .02¢

Good Luck & Tight Lines!!!

Check with your local tackle shops... most have a person they use for repairs.  You'll spend more in packing and shipping it one way that the replacement guide and labor should cost.