Here is an article on the theory and differences between the turn and hazard flashers.
http://auto.howstuffworks.com/framed...n/flashers.htm
A couple of points that jumpped out at me from this are check the bulbs first and make sure thay are the correct ones, not blown or corroded at the contacts. Check the sockets and ground wire next, grounding can be very problematic on our fiberglass bodied cars. Then have the alternator and battery tested and if good, replace the flashers last.