Good to hear you have another bike even though it is currently off the road. Rear drum brakes are very easy to sort out as they are a basic construction with minimal fiddly bits. WR6133 has it summed up on what to do. Lets hope there is no damage to the drum itself otherwise you would need to get it skimmed but that is rare. I am in Salisbury so a bit far but Good luck and keep us up to date.