Blade not spinning
My Vitamix 3600 plus has same problem. Result of detachment of rubber coupling between lower splined socket from blade shaft. This is a tough rubber molding that takes tremendous punishment through years of smoothies. Mine showed some rust on the bottom of the blade shaft, where it parted. I tried gluing back together with super glue and tried to eyeball it. Of course it was off by a few degrees. When I reassembled and turned it on, what a racket of vibration! But it held. Amazing. Obviously not good to go though. So I took assembly all apart and redid it, chucking the shaft and the lower nut in the lathe. This time, all true on axis. Glue held for about a week. Right now I am regluing, this time with epoxy. We'll see how it holds up. And meanwhilst, I'm researching replacement parts! I'm not too optimistic about the epoxy.