Freezer making noise & left side of the freezer (on...

GE upright frost free 20.3 cu.ft. freezer,  model #FUF20DACRWH, manufactured in 09/98.  Freezer located in basement of house.  Never had problems.  Two weeks ago, I opened freezer and searched for item.  Since I had door open, the motor began to run to keep freezer at correct temperature.  When freezer began to run, the noise was unusual from what it has always been.  It was a whining noise, then a scratchy noise.  I closed the freezer door and after a couple of minutes the noise stopped.  For past two weeks, I will hear the noise when I am upstairs.  I will go to basement and slap the back of the freezer and the noise stops.  Throughout the day, the noise will come and go.  The past 2 days, it has been more frequent.  Normally the outside of freezer on the left (as you face the freezer) is a little warm, but it is now very warm to the touch.  To date, the freezer is the same cold temperature inside as always.      I have investigated the problems as follows:
I listened to see if I could determine where the noise is located.  Today, I removed some of the items from mid to bottom of freezer.  I heard the noise coming from behind the panel to the evaporator fan area.  I removed the panel screws and opened it and it was where the noise is coming from.  So far, I have not been able to get the noise to reproduce.  It is coming from that area.  When I adjusted the temperature and got the freezer motor to come on to keep the temp cold, the evaporator fan was running, but of course, the noise never reproduced.  I just placed the panel back against the evaporator fan and have the freezer on the same temperature as always and I am waiting for the noise to occur again.    I don't know if the evaporator fan is getting stuck or not.  Can't figure it out ---will be better when the noise happens again.   My concern is the outside of the freezer on the left side is very warm---probably twice as warm as it should be.   (I have another freezer in the same room and the left side of it is the normal slightly warm temp.)      I am concerned that when I am not home something could happen to freezer.  Please help---sorry for long post.  I am not that experienced in appliances, but went to appliancehelp.com and found the diagrams for my freezer with parts that can be ordered.  Problem:  I don't know what parts do what---- and what symtoms indicate that a particular parts is not working properly.      thanks for help   -- not familiar with this website and how you respond.  My e-mail is einig1@netzero.net.        Thanks,   Debbie