Hi Dan -
Could be a few things, some fixable and some not. If it's a broken wire inside the hose, that's probably not fixable. I don't think the CH620 hose allows you to cut back a few inches and reconnect like some other hoses do.
It could be a poor contact in the swivel...sometimes dust or dog hair will get in between the rings and the "brushes" that contact them. It's probably not a bad switch, and it probably also isn't a poor connection between the hose and the inlet valve, as you could fix this just by adjusting the hose in the inlet.
When you have the problem (the unit shutting off), how long does it last? What do you have to do to get the unit to turn back on? When I'm having a problem like this, I'll try to "freeze" and set the hose on the floor, then move one thing at a time (ends, middle, swivel, etc.) to try and isolate the problem.
-Owen
P.S. You're fortunate to have two identical hoses. You might try swapping the handle with the "guts" from one hose to the other, just to narrow it down. If the problem follows the hose and not the handle, it's probably not repairable. At that point, take the direct connect plug out of the wall end, then just plug it in sideways and use it for the basement or garage.