Schwintek slide fox

I know this has been discussed forever, but mine acts different. My large kitchen slide with the residential fridge will start moving out with both motors and sides together.after it moves out about 6 inches the left motor or the non fridge side stops but the right side with the fridge keeps moving. You can push it a little and it takes off and goes all the way. You hold the extend side of the switch after it completes and you hear the motors sinc or it sounds like they do. When I retract it does the opposite. The motors move the slide together for about 6 inches and the right side stops. You push it from the outside and it does just like the left side when extending. Takes off and it's fine the rest of the way in. You hold the retract side of the switch after it completely retracts and again you hear the motors try to sinc. I've tried the sinc procedure moving in and out a few inches probably 100 times but nothing changes. The rails, screws, everything looks good to me.