Hey Rich, I don't mind zucchini bread at all. That's about all I find that particular vegetable is good for.
I did get one of those after-market scraper type beater blades for the Pro HD machine and it does a good job.
I'm still trying to determine a timeline for the K45. Like, when did they start putting the white coating on the flat beater and dough hook? When did they do away with the flat lip on the bowl (which tends to scrape the paint off the pedestal if you're not careful when positioning it onto its base)? When did they start giving it a three-prong plug? On line research produces very little to help, and even KA's own on-line resource people state that Hobart didn't use serial numbers or other forms of identification that would help determine the age of their mixers. All KA can provide is a huge spread, such as somewhere between 1962 and 1979 as I mentioned above.
So far, all I know is that solid state controls were introduced in 1979, which is when "SS" was tagged onto the K45 model designation. As the pictures show, my machine has the earlier bowl, uncoated beater and dough hook, and not shown is the standard two-prong plug. The plug looks like it's from the 70's and may be the best indicator of my machine's approximate age, as I'm fairly certain the yellowed cord is original.
Today I perfomed a test on my K45 per Hobart's service instructions, which advises to hold the planetary with one hand and move the switch lever with the other. With switch in the #1 position, it shouldn't be possible to stall the planetary (except by a very great effort), nor should it slow down noticeably. It passed, but I did hear some clicking from inside the gear case and am wondering if there may be issues with big jobs such as kneading dough. Since I don't bake bread from scratch I don't anticipate any trouble, but perhaps a gear could stand to be replaced at some point.