I've read many posts testifying to the better quality of the Hobart product. But I don't recall seeing the year that things changed. Would love to know. Thanks!
Hobart sold the division to Whirlpool. Deal was made in 1985 but due to anti-trust suits was not concluded until February 1986. Any KitchenAid mixer made by Hobart has the Hobart name on it.
I also think there was a change that Whirlpool made early on to go to plastic gears and after those had problems they went back to using metal. Therefore there is a time range when the KA mixers were particularly prone to trouble.
I bought one of the later KAs for my son and myself and both have been fine. I think they were both after the change back to metal gears. I use mine pretty heavily including making bread. (I use a bread machine too but sometimes I'm doing too big a batch for that.) We also use the pasta maker and the shredder - when I'm using the shredder the motor is running for a long time. We haven't had any trouble with our newer KAs.
There is one feature in my new KA that wasn't on my 30 year old Hobart (which is still going strong for another son) - slow start. With the slow start feature, the mixer comes up to speed gradually and there is much less of an issue with tossing ingredients out.