I bought the gun knowing the rotor was stuck and wouldn't turn, I couldn't see that the spindle head was broken until I took it apart. I assume that the back of the long fin on the rotor had broken off and jammed the rotor and someone tried to rotate it through the window in the receiver where the cartridge numbers are seen and broke the spindle head. I found the end of the rotor fin inside when I disassembled it.
