I stripped down my headset to check it out recently and notice that the top bearing (1 1/8) had play forward and backwards (or in and out)

If you hold the outer ring in your fingers the inner ring will move by a few MM, whereas the bottom bearing (1.5) has no play at all.

So I figured the top bearing must be knackered, so I ordered a new one which has just arrived and has exactly the same amount of play!

Is this amount of play normal?

There should be zero play.

Have you tightened the compression bolt?

As above, are you tightening your stem, before you nip up the compression bolt?

Sorry if I wasn’t clear, I’m referring to the bearing by itself, out of the headset.

I noticed this with a wheel bearing, once installed correctly there was no play in the wheel. I would assume headsets would be the same. If it feels smooth and doesn’t have play when installed I wouldn’t worry about it.

If the new one is the same, it’s normal. Or you’re just very unlucky to receive a brand new duff one, which I doubt.

If you’re concerned, stick loads of extra grease in it, but if you do it up properly and there’s no play if you rock the bike with front brake on, then all good, just ride 😀