Tyre Truer

[Bosscat]

Recently obtained a tyre truer from a racer who was giving up but when I checked it out I cannot fit my usual mandrel as the shaft is too small. Measuring up the shaft is 6.4mm diameter wheras my usual one is 8mm.
The Truer is made by Hudy and is a fully manual 12v unit called Hudy Universal #10 2801.
Are the Hudy mandrels smaller or do I need a shim or spacer? If anyone knows or can tell me which Hudy part I need that would be great.
If any one has one so much the better.