Before considering the possibility of more power, it's best to be aware of the implications of it being a torque controlled system. To get the maximum available power, whether increased or not, your wife will still have to put in the same continuous effort as at present. So a power increase probably wouldn't have the desired result of her using less effort. The torque sensing system the Impulse uses is the same as that in the Panasonic units and it's not adjustable or alterable.
For those in your wife's circumstances a torque controlled system isn't the best way to go, but unfortunately the best crank drives are usually torque controlled.
As for getting more power from the Impulse, it depends whether it has a shunt on its circuit board, and you'd need to open it up to find out. One of the Panasonic series had one and it's the shiny "goalpost" at the left of the top right white socket numbered 6 in this photo:
Either soldering one leg of the "goalpost" to reduce it's resistance or binding some thin wire across the two legs to do the same increases the power of the motor. Be aware though that the small motors these crank units use means you could easily have the motor fail very early if delivering more power. We haven't risked doing it long term on the Panasonic units.
And as said, even if achievable it wouldn't necessarily answer your wife's problem.
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