I bought a Singer Golden Touch in 1968 and never had any problems with it, I sewed on it all the time and made all of my daughters and my clothes. However,I too have an antique Bernina, I saw a Bernina 930 demonstrated at a Quilt shop and decided I just had to have one. I purchased mine in 1985. I love it and wouldn't trade it for anything. It has truly been a real workhorse for me. I have (knock on wood) never had to have it in the shop. I had several friends purchase the computerized Berninas when they came out, but I decided I didn't want the hassle of dealing with all of the extras and the costs down the road when something might go wrong. I often piece my blocks on my FW, but do my quilting on my Bernina, I don't have a LA.
I agree with others, I would definitely contact Bernina and let them know, that you bought a LEMON and at a high price too. Ask them to replace it. One should not have to have their machine in the shop more than at home to use. Good Luck. I love my Bernina and my FW's. I still have my old Singer Golden Touch, should get it out and use it some or sell it.
I can't judge other brands, as I haven't tried them, and machines are just like cars, clothes and appliances, everyone has their own choice, that's why there are so many different brands and models.