Looking around, I see that the Hitachi F1000-A planer/jointer combo machine you have, looks very much like the Hitachi P100F, which is just a thickness planer, with no jointer on the side.
I see that Tool Parts direct sells the setting gauges for that tool >> Here << Ref#141 part#973852 for $15.45 a set of two. These setting guages are used by other Hitachi planers as well. I don't know for sure if this is the right set of gauges, but, it is something to look into.
I'd contact Hitachi about getting a parts diagram and an owners manual.
The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
William Arthur Ward