I have a late 90's Lopi Spirit (DV NG 4" B-vent) and have a problem. The pilot light is randomly shutting off. The times where I've caught it happening, it has occurred while the burner is engaged. There doesn't appear to be a pattern of when this happens. Sometimes it will go weeks and be fine, others (like the past 2 days), it shuts off several times a day and needs to be reignited. Before calling in a repair person, I thought I'd check here first to see if there were some things I could trouble-shoot. Any ideas?