The first thing I would suggest would be to check the bearings; you could have cracked cages in one or both of them and that would cause the loss of torque you're seeing. Too much or too little oil could also be precipitating this. I know you posted this yesterday, but if you're still having trouble with the handpiece you can call one of my repair techs at Garland Dental and they'd be happy to give you some over-the-phone assistance. The number is 1-800-981-6414. Hope this was at least a little helpful!