Leigh,
My deepest sympathies - just let me know how I can help! It may be possible to repair the pen but it would probably be as cheap to find a replacement. Unfortunately, I don't have a spare in the same material at present. The nicest item currently in my 'for sale' drawer is this Dinkie 526 writing set (no. 20 set, dating from about 1932), both pen and pencil are in superb condition and fully working!
Click to view attachmentDinkies have two favoured places for breaking, one is across the barrel threads (which can happen even to experienced repairers dismantling a pen that hasn't been opened for decades), and the other is across the centre of the lever box, where the barrel is already slightly thinner because of the groove holding the lever pivot ring. If these are repaired after breaking, a very thin brass collar is used inside to ensure the repair is strong.
Remember, old Dinkies never die - they just go to the great spares box in the sky...........
Andy