CHICAGO (AP) — The online insurance marketplaces at the heart of President Barack Obama's health care overhaul are showing signs of trouble handling the volume of consumers on the first day of a six-month open enrollment period. Federal officials are aware of the website problems Tuesday and are working to address it as quickly as possible. U.S. Health and Human Services spokeswoman Joanne Peters says officials "have built a dynamic system and are prepared to make adjustments as needed and improve the consumer experience." The site for Maryland, which is running its own exchange, displays a message saying "We open at 12:00 noon on October 1st." Callers to the federal call center where consumers can get help by telephone have reported long wait times.