My pilot is on. However, when I turn on electrical power it does not ignite the full flame in the log. Would the problem be electrical or gas flow? Any comments or advice would be appreciated.

I am not familiar with the Marco brand. But what you say is consistent with the general view that conventional fireplace designs send most of the heat up the chimney. Since you have tried adjusting the various settings that you can adjust without improving performance, maybe you're getting the best you can from a poorly designed system. Maybe that's why they are no longer in business. The only other thing you might do is to find out if neighbors have a similar setup as yours. If they do, and theirs performs better than yours, then yours may have been improperly installed. You should get yours checked by someone with expertise on these things. If theirs is about as poorly performing as yours, there's probably not much you can do unless you want to spend money on a new installation. In that case, look into a Direct Vent insert, but that will cost you more than a few dollars.

I am not familiar with Majestic. I assume it is not a sealed system -- not direct vent -- and you open the flue when you light the fire. Is there a possibility that a downdraft is putting out the flame? It might be worth trying to have a fire with the flue not fully open, if it's possible to close it just a little bit. I'm tempted to ask if the problem occurs more often on windy days, but I have a feeling that if downdraft is the cause, it would happen irrespective of the amount of wind. This is just a wild guess. Another test you might try is to open the flue and take a sheet of newspaper, light it on fire and place it near the flue opening. The heat from the flame should rise and create an updraft. Once the updraft is going, turn on the gas and see what happens. If a downdraft is the cause of your problem, and if the updraft from the newspaper flame is self-perpetuating, you should no longer have a problem. However, if your system is direct vent, it is quite possible that one or both of the vents in the sealed system are the source of the problem. Fixing that would probably require some professional expertise. Try to find someone other than the one who did the installation. You need an expert and impartial opinion.

I don't understand the complexity, pull it up and replace it with firebrick