Grinder control knob just spins

The grinder control knob doesn't adjust the grind. When trying to adjust (turning slowly by number) it simply spins. Nothing happens. Feels "stripped"

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0