I edited my earlier post, but the wedge isn't stuck in there.

I can see right down to the wheel, and it looks quite smooth at the sides. I'm not too sure what's going on.

I might just leave it the way it is. It looks quite weird, but i'm a bit of an odd guy. I've cycled it around, and it's perfectly rideable.

The new stem is in far enough. It's really long but, if I reach in from the other side, I can't touch the wedge of the bike. There's definitely more space I can move it down into but, for some reason, it refuses to go down any more.

Like I say though, I might just leave it as it is. No bike thieves are going to steal it, that's for sure!