Is your gas fireplace producing an unsightly flame?   A few things to consider:  Has your gas pipe become clogged or rusty over the years and needs cleaning or replacing.  When the pin holes in the gas pipe become clogged, the proper oxygen cannot flow.  This will produce an intermittent blueish or yellow flame most of the time.   Take a wire brush gently brush and clean the gas pipe and pin holes.  If that doesn’t improve the flame, it may be time to replace the gas burner pipe.  Also new sand and repositioning your gas logs can also help.