Hello, first time poster looking for some help.

I just moved to Chicago and brought along my bike - it's a Raleigh C-40 that hasn't seen regular use in 10 years. It was definitely a kid's bike - there's a little wear and tear, but for the most part it's just fine for my 6-mile daily commute. Or it was. I rode it for a week or so, then on the way home one night, the front wheel was horribly wobbly. I tried to tighten (what I now know as) the QR skewer, but it didn't help. The wheel was still very wobbly.

When I got home that night and took the wheel off, I noticed there were two black nuts, one on either side, that were somewhat loose. I tightened them, and put the wheel back on. Now when I tightened the QR skewer and closed it, it's still loose. I even held the nut with a wrench and tightened the screw, but still it's loose enough that when I test rode it the lever would spin along with the bike wheel. The wheel doesn't wobble quite so much anymore, but there's still a little play in it.

Any ideas what to do/how to fix it?