I used to own a Doodle Bug where I thought the jet bumpers were a little sluggish. Williams did not switch to DC power for the bumpers and slings until a year or two later. At the least, replace all the coil sleeves with new (plastic) parts and wax the ring and the plastic skirt. That often helps a good bit.

You can always try switching the transformer to high tap as that is easily reversible and you can see how it plays.