Why not just try putting a bit of tape around the expander plug you already have?
Originally Posted by
IthaDan
I'm having trouble believing that a stem would let the steerer slip through without falling out of alignment with the tire.
I can see it; there's no rotational force strong enough acting on the joint to cause it to slip, but the much stronger and purely vertical/fore-aft pounding through the headset is enough to make the stem creep up over time.