39 -027E with different sized ro ller

I ordered and received a operator arm for my casement window. The arm is the arm that fits same as the old arm. I have a problem with the 3/16 x 9/16 plastic roller. The old arm has a metal 1/16 x 9/16 roller.

I looked on your website for a track to accomade the new roller and the tracks I see on the site mount from the side. My track mounts from the bottom of the window. The old track is 5/32 x 5/8 x 133/4.

Do you have any tracks that mount from the bottom to fit the plastic 3/16 x 9/16 roller, or an arm with the 1/16 x 9/16 roller. I am afraid to mount the track to the side of the window.