I overheated my Dewalt 987 drill using a holesaw. For the next week or so, when pulling the trigger it would be intermittent, but it would work. After about 2 weeks while using the drill the battery started smoking and became extremely hot. Assumed the problem is with the switch. Put in an old battery pack and burned it up too. Before I buy a new switch, any info would be helpful, I don't want to burn up another battery.