This is about a 90's Firebird GTA with an automatic transmission. I took the shifter **** to be reupholstered, but after getting it back, it no longer shifts properly. It seems like the mechanism under the thumb no longer reaches the white rod that releases the shifter from P.

Since I couldn't find an exploded view of the internals of the shifter button online, I’m wondering—based on this photo—if any parts might be missing? According to the upholsterer, no parts were lost during the work, but maybe something fell out during transport.

The problem is, I don't know what exactly might be missing, so I don’t know what to look for. Can anyone help?

 

Looks right, make sure the rod lands in the angled slot

 

It seems to me that this is exactly the problem — the rod doesn’t reach that far. Here’s a photo showing the maximum it extend. As I understand it, it's supposed to reach further in, correct?

 

Yes, should be sticking out of the metal a bit.

 

This doesn't seem logical at all. Even when I extended the white rod by 3mm, the gear shifting doesn't work correctly. I can shift between some gears, but not between others (e.g. from 2 to 1). However, when I extend it by 4mm, it behaves as if the button is constantly pressed. It seems to me that the white rod is the correct length, but there should be a component inside the red circle that gets pushed downward (for some gears it needs to be pushed a few mm more, for others less – that's probably why the button has such a long travel...)

 

Does that little black piece fit in the space in the red circle? Looks like that piece gets pushed down as the button is pushed in. Because that "red" section looks like a ramp. So if the white rod fits under the black piece, as that black piece is pushed down. The rod would move down as well.
That black piece also looks around 3-4mm thick. Somewhere in between the spring fits in there. Maybe what's missing is whatever holds the button from popping out. Of course i could be wrong as im just picturing in my head how this works from a picture on the net.

 

I found the solution. All the parts were correct, even the white rod was the right length (it doesn’t actually need to extend further inward). The important part was the order in which the internals are inserted into the gear lever handle. The spring needs to be positioned exactly right around the plastic. If it's even slightly misaligned, the button won't go in far enough (maybe by 1–2 mm), and that's enough to prevent it from pressing the white rod down sufficiently. I first placed the spring standing on the plastic insert and then lowered the casing around the whole thing. That way, everything aligned properly and it works now. Thanks for thinking along with me.

 

Glad you figured it out and posted. This will help others who run into the same thing