Rewiring my Workhorse 5 ballast?

Hi, I've got a Workhorse 5 ballast driving a single 96 watt PC bulb.
It's turned out to be too much light for the tank, so I'd like to
drive the bulb at a little lower wattage. Unfortunately, I lost the
documentation that came with it, and I couldn't find the info I needed
on the Fulham website, so does anybody know how to rewire this ballast
to do this?

I'm assuming that I somehow would take only three of the wires and run
the bulb off those, but I'm unsure how to arrange this exactly. That
would be about 72 watts?

Also, if it's possible, this wouldn't damage the bulb, right? Might
it even increase its lifespan?

Thanks for any info!

Kristen