A situation update. I was using a clip to attach to the battery, charging and discharging (testing) it. I accidentally pushed the charger off the desk and it tore off a bit of the tab. It is now very small, but I can still attach the clip to it. Just.
Here are a top and bottom views.
One can see how originally the tab had a spot welded attached (see -ve tab) which was accepting solder (see 2nd view). The +ve tab is now very short and probably it will be physically challenging to spot weld anything to it.
I am close to accepting defeat but if anyone thinks it can be saved then I am game to fight on. Just for fun, financially it is not worth it of course.
On the positive side, the batteries do provide 1450-1500mAh as advertised.