was given this old grinder mixer in a trade and would like to use it to grind and mix a wheat based ration for pigs and poultry. freed up hammer mill today and ground hay and shavings through to clean it up. the chain driven mixing portion doesnt work as the gearbox under the mixing tub is frozen pretty tight, \thinking its the vertical shaft attached to the mixing auger. cover was off the gear box not sure if it used to be filled with oil or what. any advice on how to free it and lube it once its free. also where to find a manual and what rpm to run my tractor. also hammers are worn on one corner if i can get this thing working how do you turn them? thanks for your help