This is normally a problem with the belts or gears that are part of the loading mechanism. sometimes the gears get out of timing.
Whatever is causing the problem, there is no easy fix that is designed for the end user to perform besides unplugging the unit for about half an hour, this resets the micro and it may or may not help.
I work at an authorized RCA repair center and I am sorry to inform you that RCA does not supply parts for any of their audio equipment any longer.
If it is under warranty you can get an exchange from the retailer you purchased it from or send it directly to RCA. You can contact them and/or download user manuals at this website:
http://support.rcaaudiovideo.com/
If it is not under the warranty it is very unlikely that it can be fixed.
RCA does not seem to care about the customers of theirs unless it is within warranty coverage.
If this information is of any help for you, please leave me a good rating or reply back if you need any more help. I am always willing to offer assistance.