how to fix? major wear of rack & pinion electric slide

X2 on broken pinion tooth. That would explain the slide moving out on it's own if the pinion stopped where there was a tooth missing that should have been engaged with the rack. Could also explain the rack getting chewed up as the 'mesh' would not be right each time the missing tooth passed the rack. As long as you are on a level surface the slide shouldn't go anywhere when you remove the drive motor/gear assembly. Is this slide a bedroom with the drive unit under a panel under the bed?