This is a hammer/drill. Working fine for two years. Now: works okay forward and reverse. But when I select Hammer setting will work okay without a load. As soon as I try to drill/hammer on a cinder block wall it aill stop after 3 seconds. Then I reset by putting in reverse, taking it out of Hammer setting, putting it in regular drill setting and it works again. But will stop again in 3 seconds when working on Hammer. One for the engineers? .