DIAGNOSIS Excessive heat in the hammer case area indicates lack of lubrication. The factory grease has broken down or leaked out.
FIX The hammer mechanism needs to be cleaned and re-greased with Milwaukee specified grease (like 49-06-4010). This requires partial disassembly.
IF THAT DIDN'T WORK The needle bearing on the anvil is failing, creating friction heat. The bearing and anvil assembly must be replaced.
HEADS UP Continued use with low lubrication will seize the hammer mechanism. This is a maintenance item for high-use tools.