I usually put a tiny dab of blue loctite. Once, while I was fiddeling with mine, one of those hex head screws took off to never-never land, so one of my drivers has a phillips head screw and washer holding the rod on.
While you have it apart, pull the plastic inserts off the front and rear drivers, take out the little phillips screw holding the driver to the axel and put a #4 flat washer under it. You'll see it fit inside a recess on the insulated washer that's already there. Again, put a tiny dot of loctite on the screw. Leave the front drivers loose enough to work back and forth just a little on the axel.
While you have it apart, pull the plastic inserts off the front and rear drivers, take out the little phillips screw holding the driver to the axel and put a #4 flat washer under it. You'll see it fit inside a recess on the insulated washer that's already there. Again, put a tiny dot of loctite on the screw. Leave the front drivers loose enough to work back and forth just a little on the axel.