Spindle for broken lock handle

Our 82-107 Thumb lever should be able to replace the broken one, spindle and all. I advise however making sure the mortise lock in the door wasn't the cause of the thumb lever breaking. To do this, remove the handle set from the door and try manually throwing the lock with a slotted screwdriver. If it doesn't budge, it means the mortise lock itself is broken and needs to be replaced. See our 82-218.