Mortgage rates began climbing again last week, and that took a toll on refinance demand. Homebuyers, however, seem finally to be ready for the spring market. Total mortgage application volume fell 1.6% last week compared with the previous week, according to the Mortgage Bankers Association's seasonally adjusted index. The average contract interest rate for 30-year fixed-rate mortgages with conforming loan balances, $832,750 or less, increased to 6.37% from 6.35%, with points remaining unchanged