Corner Block on bifold door

Hello:My right bifold door came out of its track. I had the guys from Building Maintenance come to my apt to fix it. They took out the corner block as shown (#1 nd #2) and said it was cracked. They wanted me tind a replacement part so I went to 4 brick-and-mortar stores, but no luck. Then I found your comppany and it looks like you might carry an identical part. They said if I have the part, they can come and re-install the door back to its track.The only markings I see on the corner block is "26-001" on one side, and a "Gx" on the other. I tried to look for "26-001" but it's just a Release Lever. Corner Block # 23-407 looks more like it.Can you help me with this problem?Thanks,Florina 

So I got the corner block #23-407, but the maintenance guys could not install my bifold door because the part does not have the white part where [7/16" diameter] is pointing. I am attaching a photo of my original part. The red arrow points to the white part whch runs inside the hole indicated by the 7/16" diameter. The green arrow is a part that the guys say is attached to the white part.The guys need those white parts to install the door.Any help would be appreciated.