I how frustrating it is to have issues with your vacuum. There could be one or two broken parts preventing the cord reel to lock and hold. It most likely has broken pawls or a broken hub. Generally the cord reel is replaceable as a complete assembly. The cord for this model is KC99NDGWZV06 and you can order it from this link:
Sears Parts Direct.
As for the height adjustment, in order to get the clean ability that is required it does develop some drag with the suction drawing the nozzle against the carpet. If you happen to have a deep pile carpet with a thick pad it may very well be hard to push. If you have it set to low it well tries to snowplow the carpet pile and cause extra drag. If it is set to high it will not engage the roller brush enough to help pull the vacuum forward on the carpet. In some cases you may need to set it at a level where it will do a good cleaning job and yet is not so hard to push and pull. If you are not seeing a difference I would suggest that you replace the adjustment. The image below will provide the instructions on how to do this. Lastly the axel bar. I was not able to find any information on this part. If you could please reply with a few more details, like where did is far off from, I can then provide a more detailed answer. I hope this helps. If you need further assistance, please reply to this thread. Thank you for using Manage My Life.