Install grease fittings first. Then use a rubber mallet (Do not use a vise on these) to gently tap BOTH bushings in each end, Pack with grease inside and on pin. With opposite side on a solid surface use a mallet to tap the steel pin all the way in. to Once the bushings are properly installed and a arms are on the machine, use a grease gun connected to the grease zerk fittings to pump grease into the bushing. You should pump grease until you feel resistance and then stop, do not force grease in after you begin to feel resistance as this could damage the O-ring seals. You should try to pump grease into the grease zerk fitting at each maintenance interval but after the initial installation they should not take much, if any grease.