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1/  RCA SJT/SKT CED player - turntable makes rubbing noise and the picture is unstable.
 
You have just received that " nice working" player that you purchased via the Internet.  The player was shipped to you by common carrier.  You try out the player and find out the picture is poor and something inside the player is making a bad rotating noise.  There is a good chance that your nice player was not packed with enough padding under the player and the box was put down heavily or dropped.  Now the turntable spindle has broken away from the turntable platter and the turntable is too low and rubbing on the player chassis as it rotates.  If the spindle is still tight in the platter and only moved a small distance there might be enough range in the turntable height adjustment screw to move the turntable up until it is rotating freely.  This adjustment is done with a small hex key inside the hole of large 1/2' nut in the center of the metal base of the player.  The hex key is size is 1/16".  See instructions in 2/ below.
 
If the adjustment is out of range the turntable spindle must be removed from the platter and reset. First push out the spindle and clean it to remove any oil.  It can be cemented back in using a small amount of super-glue.  The gel type works best as it sets up slowly and will allow you to set the height of the spindle in the plater.  The distance -see pix is 30/32" inch. Allow the glue to dry and then remove any surplus that is on the spindle.  Re-oil and spindle and install the turntable in the player and adjust the height screw.
 
  2/ RCA SJT/SKT player turntable height adjustment
 
The RCA Service Manual calls for a special guage to make the height adjustment, but the following method will give a good result without the use of a guage.  You will need a 1/16" hex key ( allen key), a videodisc that will play past 55 minutes ( Start Wars is an example) , a pile of heavy books to support the player.
Method.  Support the player evenly on the books to allow access to the hex nut in the center of the player base.  Insert the key into the hole and make sure the adjustment screw turns.  Sometimes it is stiff.  Connect the player to a TV set and play the disc. Turn the hex key.  Clockwise - turntable goes up and counterCC it goes down.  Too much adjustment in either direction will make the turntable scrape on a part of the player.  Begin the adjustment sequence by roughly setting the height in the center of the range.  Now view the picture quality at approx 3 mins in from the start of play.  Note the picture video noise content ( grainyness).  Now advance the play to approx 55 mins.  If you hear any scrapping noises make a small adjustment of the hex key to eliminate the noise.  Carefully looking at the grainyness in the picture, adjust the hex key until the graininess is minimum. Then go back to the 3min part of play and confirm that the noise is the same or less. 
Expected result- The turntable should not rub and the picture quality will be the same from the start to finish of the disc. End.