Sliding Glass Door leaves black graphite spots on the carpet
 

We have cleaned the sliding glass door tracks between the living room and lanai several times but keep getting black graphite marks on the carpet. The lanai is glassed in so it is not outside dirt. I suspect that the rollers have gone bad. Does anyone have the same problem and know where to get replacement rollers.

Track is aluminum and unfortunately aluminum oxidizes bleeds
Perhaps an anodized one could be installed

I have seen replacement rollers at ACE hardware (Wildwood) and I think also at Lowe's (466a). I have not replaced these yet, so I am not familiar with the sizing requirements. Some dry (spray silicone?) lubricant on the tracks MIGHT eliminate or limit the flaking of the aluminum. If you wheels happen to be plastic, try metal ones.

We had similar black marks on our carpet in our PV near sliding door. Had carpet cleaned, company told us spots were coming up from concrete. Had carpet pull up, sure enough more black spots under carpet that had not come through carpet. Not sure if this helps but for us not the roller

I'm not sure, but could the black marks be from the air flowing under the door track? This happens often on carpet near interior walls when the air flows under an interior wall. The dirt in the air will stain the carpet because the carpet acts like a dirt filter. The solution is to caulk under the sliding door track or along the inside or outside edge of the track.

Thank for the replies. I believe it is the rollers or the aluminum oxidation since the lanai is glassed in and no wind born debris gets to the tracks.