Can you post a picture of it so we can get a look at what might be wrong?

As you can see the adjustment knob came off. I assumed it wou ld be threaded but it isnt. I cant figure out what holds it in place.

Ahh, I see. It's an easy fix. It's a pressure/friction fitting. All you have to do is to add some more friction. There are many ways to achieve it. One thing you can try is a little bit of white epoxy and apply just a dab of it into the knob and then press it on. After about 3 days of curing, that knob will never come off again!

Another idea is to wrap a little friction tape around the shaft and then press the knob back on.

You could also apply some thread locking liquid to the inside of the knob and press it on.

The way that fitting works is that there are "flutings" on both the shaft and on the inside of the knob that were just a bit too big to slide together easily. But, with a little pressure, the metal flutings mesh together and lock the two pieces in place.

Sometimes, people will force the knob ****her than it can go and these flutings get sheared off. As a result, the friction is gone and the two pieces don't stay together. So, like I say, you must add some new friction to the fitting in any number of ways. Hope this helps.

Thanks, that makes sense. I was figuring on trying epoxy but now I will know why it works!