steel roller for patio door screen

Patio door screen has plastic track screwed on (and adjustable) track at bottom. Track opening is 3/8" wide in which are two steel rollers 1" diameter; their axles consist of a thin metal shaft size of a thin nail, estimate about 1/16" which extend through sides of track; this only way secured to the track. One of these rollers plus its axle is missing and need replacing. Can you advise or help me out?

I know it is a small part maybe not worth your bother. Cannot find it pictured anywhere: hope to replace rollers without additional hardware for affixing new kind.
Thanks.