I have an older model Heat-n-Glo system Model 6000DVT. It was installed by the builder when I moved in my house back in 93. Sad to admit, I haven't done much with it as far as servicing over the years and that might be catching up to me. Now when I use the remote (mod. AT85P) to turn it on, I hear the click inside the fireplace, but the fire won't ignite. Eventually after 3 or 4 attempts, it will lite, but then go out after 15 minutes or so. I had planned to give it a good clean up to see if that will correct the problem. I have the gas already shut off at the cut-out lever and could use some input on what to inspec and clean. Thanks