PPS
This is what I do to check my hammers/flails
I am not suggesting that anyone else does this

remove spark plug cap, and if really really wimpish, back of the spark
plug to remove compression,,,,

reach down the chute and push/shove/rotate the blades incrementally
till, wth the other hand, feel, up through the outet shield, the
hammers enter the output grill, check that each is free to move.
some may be a bit stiff to your fingers, but centrifugals when under
power will be no bother to them !