There are two AA size cells with solder tags solders to a PCB
incorporating a charger. But, nowhere does it say what type of
batteries they are.

I'd just use NiMH. If it originally had NiCd, then it will just take longer
to charge in proportion to how much higher capacity the new cells had to the
old, unless it has a sophisticated charger, which will probably work out
what to do itself.

Christian.