Checking the machine to make sure that it is working properly should not insult the repair person. It should be an opportunity for him - or her - to show how skilled they are while you are there!
Every time I read threads like this, I am again thankful to have one of the best Bernina shops - for both sales and service - less than half an hour from my home. Love, love, love Penn Yan Sewing! Just spent some time there yesterday (see my thread
http://www.quiltingboard.com/main-f1...ml#post6998193) and as always, they were wonderful to work with - both for my $3 repair and for a possible sale.