How did you hold the rack to prevent it from twisting when you unscrewed the tie rod end? If you didn’t hold the rack still but instead twisted the tie rod end off with the rack housing holding the rack in place you may have damaged the rack housing. Because you failed to recognize and remove the lock washer you put a great deal of torque on the rack. I use a 24" crescent wrench to hold racks when removing and installing inner tie rods and that’s after freeing up any lock washers, etc.
I have watched several youtube videos for insight into repairing weed-eaters, chain saws, etc and found some helpful but quite a few are a waste of time and I assume that some of the videos on rack and pinion repair are good and others not so good. Your inexperience makes it difficult to discern whether you have damaged the rack or if you might be able to salvage that lock washer. As for staking a standard washer I suggest you don’t try that. Doing so could damage the rack. A soft metal washer that is easily bent is needed.
But good luck