Hi Ken,
Have you formed an opinion of your estate sale purchases yet? I wouldn't be surprised if the online reviews have been filled with recent comments about the new belt-drive machines that came out shortly after these 600s were marketed. I sometimes think people and even retailers don't know that they are reviewing the wrong product at times. Back in the 2010 time frame, most of the reviews of this line of Kenmore machines were positive, with mostly comments about washer noise as the main negative sentiment.
To answer your question, believe it or not I have not used this washer yet, and the dryer still remains new in box. We lost my Dad in May 2013, and the previous 12 months I spent very involved with family. Back in the groove now so to speak, I have to decide what to do with this washer, as I am thinking it might be better off, with the dryer too, being used by someone who would appreciate it as a daily driver as I will never put a lot of miles on it. I did get my '93 DD out the other week for its first use since 2008. I think I have used it now six or seven times. I like that washer a lot, but I don't need two DDs.
I would imagine that you are happy with the 600s?
Gordon