Sandy, just a hint, ask him to take the head off and show you where the thread and lint was in your machine. Then ask where to oil or there maybe places on the cogs on the inside that need the heavier lubricant. It's a way to get to the inside. Most machines they only do the inside once a year. He may just think you mean under the bobbin, etc. for cleaning.
Had to take the head off of mine yesterday, got to the last bit of thread on the cone and there was a knot in it so it was stuck there. Without knowing what it was caught on I didn't want to just give it a tug and go for it, good thing too...it was stuck in the brushes. All fine now.