It is probable that the centre plastic bush is distorted from removal off the pinpoint and then onto the shouldered axle. I have a good supply of the centre bushes and I will pop some in the post tomorrow (Monday) They are a push fit into the centre of the wheel, the old one being hooked out from the back with a narrow pointed tool (small bradawl or dentist tool etc). They are tiny!
In terms of getting the wheels on straight, I must admit I use a wheel press as I could never get them on straight manually. It is certainly possible using the BtoB gauge you have provided the faces are parallel and you press them in with a vice to exert even pressure. The other thing to do is to take the edge off each end of the axle to ensure you get a smooth entry