I've only had a 1960s 730 for keeps, for years now. It sews fine, absolutely not fuzzy when it comes to thread, Coats, Gütermann, Aurifil, cotton, polyester, linen, metallic, pearl embroidery yarn (special large hole needle). If these machines are fuzzy with thread I suspect they need a good clean or adjustments.
I bought some thread in the local sewing shop today, and there were a 707 Minimatic for sale. It looked slightly smaller than my 730, both 1960s models, in good working condition, not sure if it was recently serviced or just recently handed in, they asked $180 for it. That's the same price as all the much newer and more or less computerized models they had on the used machine shelf.