Actually the best thing would be to cycle the valves so they would not stick... once a year would probably solve all of these problems, at oil change or so so you could do a general maintenance. I will link to some websites below, and my battle with the check valves, I ended up purchasing a used set which one was stuck, I did repair one successful, however I have a lathe so keep that in mind, and it was a huge help. If these valves had been made to disassemble there would never be an issue with the valves at all, they are that easy to fix once you get them apart.. but you have to get them back together with good workmanship, and no worries about holding !!
If I were to do it again instead of tacking with a welder/brazing I think it might be better to cut them using the lathe, then leave a small shoulder to press them back together using epoxy for a mind ease.. and max press fit tolerance.
On edit if your hydraulic check valves are failing/collapsing when the engine is cut off I think you have either weak or broken springs inside, they should hold up by them self as the spring is pretty stout.
http://cubfaq.com/relief1.html
http://onlycubcadets.net/forum/showthread.php?t=473