A looming debt payment no longer looks ominous for the cash-strapped authority that oversees a number of parking garages in downtown Richmond, but another big shortfall already is in sight. The city advanced more than $655,000 yesterday to the Broad Street Community Development Authority to make up a shortfall in the debt payment due June 1 on bonds that were sold six years ago to pay for new parking, demolition of Sixth Street Marketplace and public improvements to the declining downtown retail corridor.