OK I tried a # of different drivers, and I know the headset works elsewhere so it's not the problem. That leaves hardware (the external jacks (mike/ears)) or software (drivers). As it happens in trying a number of drivers, I had to twiddle the jacks in and out to alternate between internal and external sound. On one attempt I could hear static and with some fiddling eventually one audio channel. Doing the same with the mike jack I could eventually get this to work using a toothpick to hold it more securely in.
Conclusion? It's the jacks, unfortunate that this
Not sure on options with this as the identified problem. New motherboard for a Dell Inspiron N5050 laptop which I've found a really nice machine and (had) hope(d) to upgrade? Possible to replace just jacks/jacks assembly? Quick fix is a USB stick to accommodate headphones/mike jacks for headset- under $10. Longer term, if I need to get a new motherboard maybe best look at a new machine entirely- as it is this unit has a Celeron processor and I was looking at putting an i5 in- total cost for new keyboard/8GB RAM/USB Stick/i5 c$150-200.