Hey Stu . When you done up the flipper pawl onto the shaft did you leave just a small amount of gap between the pawl and the bottom of the flipper bushing (ie. when it's done up can the flipper bat and shaft lift up through the bushing - just slightly . 0.5mm at most ) . If there is no movement there it could be that there is a bit of drag between the flipper bat and the bushing .
You can also have the opposite effect if there is too much gap if the pawl is down too far the plunger will not be in direct line with the coil causing the plunger to drag in the coil sleeve .
Not sure if you have already checked these problems , and /or if this info helps you out but thought I'd throw them in just in case .
Cheers.
