What can cause an Aspire 5610 to have intermittent audio, both speakers and headphones?

My Acer Aspire 5610Z lost it's audio to the speakers. The earphones worked fine. I replaced the motherboard with a 5610 board to be able to have the 4Gb memory support. I also replaced the speakers thinking they were the cause of the lost audio, and the speakers were rather bad looking also. Everything is fine with the added memory that the 5610Z would not support. Now I still have audio issues. Sometimes it will be fine and other times the audio will be absent from the speakers and the headphones. When I run diagnostics I am told that the speakers and headphones are not connected. Has anyone else had this problem and if so did you find a repair for it. I am an electronics technician by trade so working on the motherboard is something I am familiar with.

Thanks in advance for any suggestions you may have.