Mortgage servicers may have to take a pay cut to participate in President Barack Obama’s programs to modify home loans and advance the sale of properties in default. Starting this month, the Treasury Department is paying companies that collect mortgage payments and examine pleas for assistance a $1,500 stipend for approving the sale of homes for less than the loan balance, known as a short sale. The servicers also get $1,000 for each completion under the government’s year- old mortgage modification program, and additional stipends over three years if borrowers stay current on their payments.