A relative recently had her main panel upgraded from a 100 amp to a 200 amp service. Since then her lights dim on occasion. When I put a clamp meter on the leads I only get a max of 17 amps on one leg and 18 amps on the other leg with all the appliances on. I can only figure that the neutral is loose in the meter box or in the overhead since that was replaced as well. The connection in the box looks good and tight.

Your suspicion that there is a loose connection is very possible. Not necessarily the neutral, could be one of the hot legs.

A loose neutral can dim lights on one leg, and increase voltage on the other, and you would see some lights get brighter.

Thank you I'm sure its going to become the blame game as the city electric company was involved in the upgrade. One more question. When I had my service put in ( by a different provider) there are several transformers involved. On this install the lines to the house are just clamped to the service lines on the poles going down the street. The nearest transformer is 2 blocks down. How do you determine the amps to the house, by line size?