I had this “Gladiator” angle grinder awaiting repairs for quite a lot of time. It was cheap but I liked it a lot because it came with a speed control and took a lot of use without complaining.
But one day it broke. The motor spun, there was a lot of noise but the output wasn’t turning. Inspecting the gearbox revealed that the small bevel gear was free in the motor shaft. The grease had some shiny specks and looking closer the key was still in the gear.
On the previous weeks it started to make louder and louder sounds but I assumed it was kind of normal for the abuse.
And then it seems that the keyway gave up and the shaft, soft as butter, ground itself between the hardened gear and the woodruff key until it became free:
I used the bearing puller to have a solid ground connection and started to pad beads to build up the missing metal. I went a bit overboard with the heat but I somehow managed to not bend nor twist the shaft. Tomorrow I’ll try to grind it back to the original dimensions.