That condition is known as epispadia... It is congenital condition, means that he was born with an abnormal opening of his urethra... Usually, this is corrected at an early age... I think that the urethral surgery done on him was to correct this condition... However, i think the condtion recurred... Have him see a Urologic Surgeon...
It sounds like its his PC muscle is weak, and its a simple exercise for him, its the same as you doing your pelvicfloor, but for hime it will help him to ejeculate stronger, but for him the more he does the merryer and once hes away he will fill it working and so will you, if you cant work it out with just how to do it, just go to pegym on there you will find lots of info.
Good luck