Finding a sewing machine dealer who is very knowledgeable about every model he/she sells is a dying profession. I have given up and buy my machines on-line and take all of them to one place to be serviced, which is two hours from my home. The last placed I used charged me a fortune and still didn't fix my machine. Told me it was "another" problem my machine was having - this was after he insisted I needed a new $125 foot control. If I don't receive good service I just don't go there anymore - and that holds true for anything I purchase. Fact is, finding someone to wait on you in most retail stores is a real chore.
I do think I'd drop a note to the owner of that store and relay your experience. He may be barely holding on and not know why.