removing bubbles from under vinyl flooring

[devildog]

A friend of mine asked me to help him remove some(bubbles) in his dining area. The biggest is 1'x2'. I researched online and  found a couple of methods. One way is to cut a cross in it with a razor knife, peel it back,add new adhesiveand roll it back down. the other was to poke holes in it and use an iron with a cloth on it to reactivate the glue.
I found out this is caused by moisture underneath the floor.

Have any of you repaired anything like this? Do these methods work? Is there a better or easier way?
Thanks, Darrell