I haven't actually done it myself. When Bruntons said they couldn't repitch my AutoProp (They've changed the design since mine), I bought a MaxProp. It's not as persnickety about fouling or maintenance affecting performance.
I was convinced (due to my lack of knowledge, and agreement by mechanics who didn't understand AutoProps either) that the prop was OK. I didn't take the advice of the knowledgeable people here and I'm virtually certain that it cost me a bundle.
You can find some posts about it if you search the conversations for AutoProp, they are probably 5-10 years back. My understanding is that you can order a rebuild kit and do it yourself.
Let us know what you find.
As an aside, I still have that AutoProp and will sell it at a reasonable price if someone wants it.
S/V Kristy SM243