How do I tighten up my headset? I've got an old bike with a quill stem, and the headset arrangement has a nut, and a textured lock ring. I presume I should tighten with a combination of a spanner and mole grip. Is a mole grip the right tool for the job?
I believe this style is meant to be tightened by hand.

To tighten, start by tightening the knurled/textured upper race a little harder than you intend it to be once you're done.

Next, add the washer and screw on the locknut as hard as you can without tightening the race any more than it already is. Too tight and you may damage the races and need a new headset.

Then whilst holding the locknut still with a spanner, unscrew the race by hand as hard as you can. The idea is to be it clamped against the locknut so neither can move.

You may need to experiment with how tight you start to get the right tightness at the end.

PS. Mole grips are almost always the wrong tool.