Can you rebuild the 73-74 heater control valves?

[WH23G3G]

I got a pretty clean heater control valve for a 74 that I need for my 73. I didn't like the aftermarket one, this one from the 74 fits up right. You can take this one apart. The plastic top comes off and on the bottom of it there is a plunger that moves when the lever is opened, a spring, and an internal vacuum port. Then on the bottom metal is the water passages with a paper gasket between. It was just clogged up with some scale. The lever opens and the plunger moves up and down when I move the lever. Is there anything else to do? I just cleaned out the scale and I'll make a new gasket.