Intermittent jake on brand new ISX15

[imalumberjack]

We have a 2018 Pete with ISX 15 @565hp around 50,000 miles, jake started acting up about 2 months ago and it was taken to the stealership ...two weeks later and a replaced turbo it came back. Jake started acting up again :-(
Driver is a good mechanic also and he says its one of the stages and sometimes it shakes the whole truck and that its intermittent. Driver thinks its an electrical issue. Owner does not have Insite, I do but there is a hatred of Chinese knock offs at there shop and if I connected I would be liable for every issue in truck from then on.
Has anyone had this issue? Maybe an explanation of how the 3 stages work? I hate to see it leave to stealership as it doubles my work load ...HELP!!!!!!