Nice stuff @sheddi That's just the sort of thing I would do, if the battery pack was to fail. Just replace the battery pack (replacing the individual cells if necessary) and go from there.
It's very rare for devices that use Ni-MH battery packs to still be in existence - most mobile phones/laptop battery packs etc use Li-Ion now instead. But the basic principle is still there, regarding disassembly and reassembly. (1x Li-Ion cell is the same voltage as 3x Ni-MH cells.)
Edit: I'd not really recommend batteries from China - yes, they're cheap, but I'd want to get that pack checked with a battery analyzer to find the true capacity of those cells. The Chinese sellers often exaggerate their capacity, and you can often get 900mAh (or similar) AAA LSD Ni-MH batteries in a pack from LIDL supermarkets - which, being LSD, means you don't have to worry about constantly topping them up to avoid them draining themselves.