It did seem like the old solid tub SQs had short lives. Kind of like Norge,Bradford,Wizard, etc. Like John said "too much pot-metal". Some of them have survived pretty well though. Martin has one I rescued from a farm north of Cincinnati over a dozen years ago. I think it is a '67 or so. I didn't have to do much. The pot metal clip holding the sediment tube had rusted through and the tube was scrapping the side of the outer tub during spin. Likely the cause for it being taken out of service. Greg told me how to fix it and I did. I was using it as a daily driver for a while. One day I was watching tv while a load was going. Suddenly a cloud of noxious smoke rolled into the room. I ran to the kitchen to find the machine enveloped in smoke. It smelled electrical. I couldn't get the front panel off fast enough. I had visions of the motor on fire. Nope, the Spin Solenoid had fried. That little thing really put out a lot of smoke. I had to put fans in the windows and ventilate the house for hours. Got a new solenoid at Fox and was back in business. I passed the machine on to Georgedon, then it went to Martin. That thing is a pretty tough machine.
Currently, I have a '68 or so I got from Greg about ten years ago. It was originally a three-speed however, a certain mad scientist cherry-picked the original motor. (Not Greg!). A single -speed replaced it. It works just fine. It does have a Quirky timer. When the temperature drops in the basement in the winter, it refuses to fill in the Wash cycle. If I turn the timer to the Rinse fill---no problem! It only does it in the cold weather. Go figya.
It has a gray, speckled Enamel tub. I like it much better than SS. Funny how they made such a fuss over SS tubs and then used pot-metal everywhere else.
Through Greg's generosity I also have one of the last of the solid tub machines. It has the larger solid tub and reversing motor. It still works just fine if a little "knocky " during agitation. Great machine, however, due to Government interference, they dropped a minute of the Rinse Fill to save a bit of water. Consequently, most of what SHOULD be an Overflow Rinse isn't because it starts agitation before the tub is full. Removing water restrictors made no difference. Oh well.
The longest lived SQ solid tubs seemed to be coin op machines, probably because they were constantly being repaired. The laundries loved them though. I saw plenty of them with pretty serious rust that were still in service.