I have just done the exact same repair as above, using a replacement washer and torx screw to re-secure the cam and spring. I managed to do this without motor removal by removing the ball casing (both halves) and then undoing the right hand side of the yoke. It's a bit of a struggle, but this will give you just enough room to get a torx driver onto the screw that secures the cam.
So far, so good. However, on reassembly I tested it and found that, while the upright lock now works fine again, the brushbar did not spin when the machine is reclined (but it did spin when the brushbar reset button was held down). So the motor is OK. Next, I'd suspect the reset module, but the coincidence of it failing when I did the upright lock repair is just too great. So I'm assuming that whatever causes the brushbar to power up when the machine is reclined was damaged during reassembly. But what? My strip down method did not require any cable removal or electrical components to be disturbed, so I'm at a loss to see what I might have done wrong. Can anybody point me in the right direction please?