DVD disc tray keeps popping out

I am experiencing problems with my LG DVD Recorder (model DR386D). The recorder works most times, however is unreliable. The tray holding the disc sometimes pops out before a recording starts, therefore the set program is not recorded. Also, quite often the disc tray will keep opening and it takes many attempts to close it before it accepts reading the disc. I alternate using 10 different discs, and sometimes it accepts them and sometimes not. The discs I use are Memorex DVD+RW Also, I note that when the power supply is interrupted (which fortunately does not happen often), the recorder has to be reset and I have to go through the initialization process each time. Is there something wrong with the recorder or have I just bought a crappy machine? I'm hoping you can help.