What is it a little metal "U" that snaps over a nub on the sill? I cannot tell from the picture. If not that what is it?

The screen door is installed in the patio door frame. The patio door sits on the inside while the screen door is outside. Both of these doors slide on two channels that are part of the patio door frame.

The screen door channel contains a track that is warped on broken. The screen door wheels ride on this track. I don't see any screws that would attach the track to the channel, so I am assuming it's glued inside the channel. The track is basically an inverted T like strip (metal or vinyl I am not sure).

I have attached some more pictures. The screen door track is towards the bottom of the picture.

Amazon has a snap on piece that might be the easy answer to your problem. https://www.amazon.com/Lower-Track-Sliding-Screen-Stainless/dp/B002QGAPLU

Thanks @krissie55.

That's very close to what I would need. However, the bottom part for the track I would need needs to be flat so that I can glue it to the channel it's going to rest in. The Amazon's track is raised from the sides.

I will take a second look at my existing rack and see if I can lift it up to find out how it's attached to the base. Thanks for the link.

Since the Amazon one is a "snap in" place I don't think it would need to be glued down, that is, if the measurement of existing one is the same size..

You are right @millworkman.

I was able to lift off one of the end of the track and it was not glued in. It's more of a snap-in kind of a track. Below are more pictures.

https://imgur.com/a/3QMsXx6

Did you click the link I included above?

Are we on the right track with this one?

Vinyl, 9/16" wide X 3/8" tall (1/2" overall height)

Thanks @millworkman, @Sammy

Yes, that looks like the closest fit. I will double check the dimensions to make sure it fits. Thanks for your help guys.

You're welcome. Good luck and hope fully it is the correct guide.

@millworkman, @Sammy

Thanks for your suggestions. I got the track from metroscreenworks and installed it today. The screen door is back in business :).

The track was a very tight fit width wise so I sanded it down on both the sides. I wasn't able to slide it all the way to the bottom in the channel so its sitting a little higher then the previous track. However I was still able to slide the screen door on it so I didn't bother sanding it further.

Thanks.