I am half way through a king pin change (4 hours to cut welded in welch plug out and remove other seized things , ten minutes to remove pin and bushes )
While i've got the hub in the vice i can 'waggle' the back plate a bit ,is this normal or does it indicate bearing failure? It doesn't squeal or rumble in use.

There will be a bit of play with the drive shaft out. If it was quiet it's likely OK.

Cheers. with everything else going wrong tonight i started to expect it to be shot as well

Ben,
that play happens because the inner bearing races are clamped together by the driveshaft nut.
Once it's no longer holding them, they will move apart, especially if a fair sized hammer is being wielded close by.

I guess you had to separate the hub carrier from the track rod end to clean up that mess on the Welch plug area, but normally I find it's not necessary to remove it.
It's not difficult to tap the old bushes out and the new ones in with the hub carrier held in your hand...

http://www.flickr.com/photos/30132857@N06/3617046904/

ken.

Don't forget the king pin is handed when you put it in!

Took some separating from the track rod end ,it was very attached. Your pic makes things look quicker ,i didn't think of that ,comes with experience i suppose
I'm following the kingpin sticky thread as i've never done this job before ,so 250 when you say handed i take you mean the way the holes have to line up..

All done ,all nice..no more kingpins jobs taken to a garage
Was in despair at one point, once the tension built up at work this week had worn off on the hammer and still the welch plug wouldnt budge
Thanks for replies.

It's very satisfying knowing you can do it yourself. I too had movement in the hub, but once the driveshaft was back on the movement went.