The bees have been inside this wall for 2-3 years according to the home owner. Because they are entering behind the electric meter base I decided that the thing to do is to make them move the entrance.
Here is the setup - I knocked a 1 1/2" hole in the wall directly below the existing entrance in the same core area as the old one - as soon as I made the hole a few bees started coming out through it to investigate. The brown piece of plywood with the hole is caulked and tacked to the blocks with small masonry nails. I caulked around the meter base and any other suspicious looking holes in the area, and left it like this for a few days so that they could get used to using the new entrance. The bait hive just contains empty frames with starter strips at this point.
About 3:00 PM Today I baited the hive with a frame of eggs / brood and a frame of stores along with the house bees clinging to the two frames and an inverted jar feeder of sugar water through the hole in the inner cover - then I added the trap out cone and the little wooden walkway so that they could walk over from the wall to the bait hive. Within 2 minutes it looked like this - bees everywhere trying to get back into the old hive.
Within 15 minutes there was a steady stream of bees walking into the bait hive.
Soon there were several bees doing this number - which I understand disperses pheromones which mean "this is home." I hung out for about 1 1/2 hours to make sure that they weren't going to find another way in. I came back at dusk and most of the activity had calmed down with only a few bees still outside the hive looking around for the old entrance. I even saw a few bees fly directly into the bait hive.
So far so good. I'll keep you posted as this goes.
By the way - thanks to everyone for all the great information and help. I can imagine that before the internet and all the helpful people on forums like this that it would have been extremely unlikely that a first year bee keeper would have access to the information needed to do something like this. Thanks.