Boot lock HB help

[Steve]

I have a new barrell for my HB boot lock as ive never had a key.

Anyone know how the assembly goes together? i got the old lock out and changed the barrell but the metal retainer which holds the lock to the body came off, i know how that goes on but there is a spring which fits at the end of the barrell then a metal piece that fit into that,,i cant see which way the spring goes on.i know the the metal part has an arm which hits the catch to open the boot

does the straight end of that fit into the back of the barrell? and how does the spring go on>? cant find any description or diagram in the Haynes manual

Cheers