Originally Posted by Boyd Birchler
I had a aerobatic 3 blade Hoffmann that had similar problems. The counterweights were in the wrong position.
If it is a non-aerobatic prop, then I agree, sounds like course pitch stops. If it is counterweighted, this sounds like a likely culprit.
FWIW, I can not change the pitch on my Whirl Wind prop by twisting by hand either, even after almost 600 hrs.