Thanks Martin,
I did try to dig into the root system but it was almost ''rock solide''. I cut off the entire side of the root mass on one side and I hope to do the same on the other part in fall or next spring. I left the canopy as is and I have noticed that the brebas have not grown much compared to the other trees. For this year and next year I am fine if this tree will not produce much. My main objective is to have this tree have a brand new root mass.
Also, there was an interesting reply from Al on GW.