if you've held the switch for several seconds after the slide stops, to resync, then also try this: when you see one end pausing or starting 'to turn'(in your words), stop, run the slide back the other way for a second or so, then try again. Do this several times if needed to get them to come in/out together. Hold the switch several seconds when the slide finishes and both end are together. Holding the switch is probably the most important part of the process as it get the motors in sync for the next time you run the slides.
'14 Thor Palazzo 33.3 compact diesel 100k+miles since '14... US, Alaska, Canada...
AND a '14 Gulfstream Amerlite
AND a '07 ForestRIver Rockwood