Sorry, I thought you meant you could not find where the battery went in. My bad.
I also fixed the link - not sure why that didn't work the first time, sorry.
Based on how you describe the battery, I will guess that you need a PX-625 battery. The good news is you can get something close to it. The bad news is that the batteries of that era were made with mercury, and those batteries are no longer made, haven't been made in years. They produced 1.35 volts.
The direct alkaline or silver-oxide replacement unfortunately makes 1.55 volts, which is enough of a difference to throw your metering off a fair amount, but it's worse than that. It seems mercury cells were popular because they were very, very stable in terms of output. They put out 1.35 volts from the time they were fresh until they were very nearly dead - a flat curve, as they say. The 1.55 volt replacements drop in voltage as they get older, so you can't just compensate by adjusting ISO speed of your film, for example. That only works when the battery is brand new, and rapidly stops working.
Aternatives?
External meter.
Zinc-Air battery from a company like Wein (expensive, and they don't last that long), but they have the right voltage and are nice and flat in terms of output.
Battery converter - not cheap, but you can reuse it over and over again, and it has a voltage regulator that not only drops the voltage of an SR44-type battery, but keeps the output steady electronically.
Have camera converted to use more modern batteries. Some can be recalibrated, some can't. Probably the most expensive option. I had it done on an Olympus RD, and I'm not sorry I did so, but really, I tend towards the 'external meter' approach.
Hope that helps.
