Slider (bottom) hardware for 4' wide screen sliding door
Hello! This looks like the older version of our 84-091 screen door roller. I think this may be the part you need, but review its specs and let me know if you agree.
Oh, I think I see what you mean. I'm sorry for not noticing that at first. Looks like the peg from the corner snapped off and is still held by the roller.
Honestly in that case your roller may very well still be in working condition. It sounds like the corner is what has to be changed. This is usually something like our 95-020, and it is a bit of a project to replace, as you suspect. It involves disassembly of the door frame to not only swap out, but to even know what size you need to begin with. That means you have to take the door down more than once if you plan on using it between placing the order and the repair itself.
You may want the help of a local professional if that's not a project you want to handle. It's definitely doable, but I wouldn't call it a fun time, either.