Circle of plastic from sliding door

[Ark]

Good morning it’s me again
Yesterday I could not easily slide the heavy back foot shut
I took a torch in the dark and discovered a plastic circle in the groove rut which I show on the photo
I’m presuming it’s fallen of the mechanism. Is this an expensive job to fix or can it slip back onto to wherever it came from and does any one know how to do this. Or do I need to go to a garage. Thankyou

 

[Ark]

Door sorry not foot

 

[jts46]

Looks like the top or bottom roller

 

[ArunAlec]

It’s probably worth changing the whole assembly. If the roller has fallen off then the fixing/ bearing that it sits on has probably been lost.
This video gives a good idea of what’s involved....

vwt5 side door rooler replacement - Suchen Videos

www.bing.com

 

[BikerGran]

The bottom roller broke on mine. It wasn't very expensive to get it fixed if I remember rightly.