Remote no idea.
Curtain most likely to be dirty runner power strip or missing pick ups on the ceramic linear motors. Remove curtains from the rail, use a gentle spray household cleaner will do, spray into the rail and use a SOFT cloth/cotton wool to GENTLY slide up and down the runner. Replace only the ceramic slide, and be careful with the pick ups. Test to see the thing fly back and forth!
If during your cleaning you find any broken or rough parts of the power strip it is u/s and you need to find a way to replace it.