A while back I had my fireplace on and the gas logs were burning just fine and then *poof* they went out. Just like that. We had someone come out and clean out the burner and it worked for awhile but then *poof* it went out again. Now I've come to understand we need to replace the thermo coupler on it. Is it easy to have these replaced? Will it be expensive or would we do better by just purchasing another set of gas logs? Anybody know anything about this or have had a similar experience??