SPIN cycle it counts down to 8 or 7 and does not go to high speed spin

We have a Samsung WF520ABP/XAA 04 serial number Y08X54AB600511H Problem : When we put a cycle in Norman,Quick Wash, Rinse and spin and other modes it goes thru the cycles and everything drains out then when you come to the SPIN cycle it counts down to 8 or 7 and does not go to high speed spin just a slow spin back and forth for several minutes. then it stops and goes back to the beginning of the cycle starting all over. It sometimes shows unbalanced load? I cleaned out the lower drain I do that every 2 months did not have much in it. I put it in the test spin mode and it ran to max speed . I have unplugged the unit and it seems to run for a few loads then goes back to the same. When it does go into high speed spin it seems to be louder than normal . we have had this washer for 5 years and we have always used it the same way . Matt Thank You again for your help.