re fitting seat belts

hi folks

i currently have sabelt 4 point harnesses in car, but want to retro fit my seat belts for short daily commutes and also to provide some better safety for my son who now pax’es without his car booster seat, so the harnesses dont fit him well enough at the mo for me to be happy.
i have the original seatbelts and have removed the pax seat to fit.
however think i must be a bit dim as the belt has recoiled into the mechanism and i cant get it to re-extend out so i can fit it to the fastening points? it seems to grip the belt with only the slightest pressure applied
any help greatfully recieved as ever, and if anyone is sad / knowlegable to know which extra bolts i need to buy to fit them back that would be cool, as i didnt get them in the box :

cheers

richbk

Try tilting the mechanism to the angle that it bolts in to the car at and gently pull, it should recoil unless it has wound all the way inn and it’s bound up on the belt it self !