Originally Posted by Ed Holland

OK Rider 888,

The bolt holding the top cover actually provides the tension which ensures that there is no unwanted movement in the headset bearing.

Loosen the bolts on the side of the stem (just visible on the right hand side of your picture) Replace the top cover and bolt and tighten it gradually untill the movement you noticed is gone. Now make sure that the handlebars steer smoothly (are not stiff) and are lined up with the front wheel properly. If all is OK tighten the bolts at on the side of the stem to lock it all in place. You should be OK

There is more great info in the "Barnetts Manuals" Sticky thread at the top of the Bicycle Mechanics section if you need it.

Good luck,

Ed