Seat belt height adjustment mechanism

Dumb title I know, I'm not really sure what it's actually called.

My seat belt height adjustment thing on my driver's side is broken, the button has no pressure to it, it just goes all the way into the piece and it refuses to unlock and move up and down.

Has anyone replaced/worked on this before?
Is it easy to open it and figure out what might be broken?

 

The seat belt retractor and locking mechanism is on the bottom.
Your pic is of what is basically a fairlead.
http://www.4x4wire.com/toyota/minutemods/seatbelt/

 

The belt retracts and pulls out correctly and everything, I just can't use the pictured part to adjust it up and down, that's the broken part.

 

Sorry, here is the double cab image. That was single cab.

 

I would assume double cab should be same as my xtracab? For the front ofc

nevermind, that is xtracab in that img there, I looked at it wrong

 

Extra cab

 

I can only guess dirt from over the years .

Unless it was treated violent often that things twisted enough it will no longer move.

the button linkage just feel apart /broke from old age pushing does nothing but move the button .

about the only way to know is take things apart and look.

 

Got it fixed! From what I'd assume was just 17 years of pulling on it time and time again to buckle up, the bolt had backed itself out and it had come loose (scarily so, it was on slightly more than hand tight). Because it was loose, it was farther from the pillar and even with the button all the way pressed, the mechanism inside it didn't reach far enough to move the pin inside of it to unlock it and let it move. Removed it, looked it over, and threw it back on to proper torque and good as new! Thank you everyone for your help!

 

I had to go outside and check my truck to see if it had the adjustable anchors. Hadn't moved it in years and forgot all about about them.