We suffered last season from sticky main sheet traveler, we always - even in light winds - had to adjust it using the halyard winches.
Upon investigation the traveler car itself moved nicely, but the old 10mm ropes had worn to "spiky", jamming at traveller pulleys. Furthermore, it looked like the rope terminating knot (instead of eye splice) scraped against adjacent ropes as well.
Last weekend I replaced the old 10mm ropes with more flexible 8mm Gleistein Tasmania. What an improvement! Now I could adjust the traveller without winches even in 12m/s gusts.
Old rope condition and new ones - photos attached