You’ll likely need a second pair of hands to help you with this. Get from the hardware store a smoke stick tester which just creates smoke and a marker to note the holes.
You’ll need to turn the hose around so instead of vacuuming it’s blowing. If you can’t connect the hose directly use some cardboard and tape to create the needed seal to guide the vacuums exhaust into the hose.
You’ll want to get the smoke stick near the vacuum end to suck the smoke into the vacuum and on to the hose.
Place your hand over the open hose end so the air has less of an exit. You’ll want to have a marker handy to mark the hose where the smoky air exits. Cloth bicycle handle bar tape is a good choice to patch the hose.