Traco Sliding Glass Door Roller

Hi, I have a Traco Patio sliding glass patio door that is getting very difficult to slide. I use it frequently as I have dogs that I let out several times a day.

My door is taller than usual - 91 inches as we have high ceilings in the living room. The sliding part is 4 feet wide and the stationary part is also 4 feet wide, so the total size is 91" high and 8 feet wide. I cannot find a model number anywhere on the door. I contact a local door dealer and he said he no longer carried Traco door parts. Are you able to help me determine what part I need to make the door slide more smoothly? Also if you would recommend a door dealer here in Pittsburgh, pa. to do the repair, I would appreciate it. Thanks. Chris

Thank you, Paul. I could not locate a metallic sticker anywhere on the door. I did, however, manage to arrange to have someone who works with doors and windows come out and take a look at it. I shared the info you provided with him. Thank you very much for your prompt reply.