My Bosch PSR 14.4 coordless drill/screwdriver has got a problem with the motor controller. Normally you can proportionally control the speed by gradually pressing the on/off button. If you press just a little it goes slowly, if you press it hard it goes fast. That doesn't work anymore and it always runs at full speed even if you just touch the button. That makes it almost impossible to use it as a screwdriver.

The three LEDs that indicate the batteri level flashes slowly, as to indicate a fault.

I would very much appreciate instructions, links or just hints at how to fix this problem. I often tinker with electronics so I have no problems replacing parts etc.

Thanks in advance :)