RE: working age of Ni-Mh
I have no problems with the suggestion to replace the batteries with new if you can. However, even new Nixx based batteries need to be checked out by charging at 0.1C for 15 to 16 hours and then checked for capacity. Some will require a repeat of this slow charge/discharge cycle before they come up to full capacity. I have had new batteries that were not at all reliable and I have also had some NiCad's that performed well for 10 years. If in doubt, replace them.