With wheels removed mark and drill the center of the a-arm with a 1/8" pilot hole. You will feel the clearance when you go through the aluminum between the a-arm and the inner steel insert inside the bushings. In several steps increase drill size to 7/32" for the small screw in grease fitting.
With a dremmel tool and cut-off wheel cut a slot in the end of a spare grease fitting to make a thread tapping tool. The grease fittings are hardened and will not be cut with a hack saw. Practice on a spare piece of aluminum until you can make threads by tapping on the tool and turning it a half-hex at a time. After practicing, repeat this procedure in the A-Arm. Do not make threads too far! Just 2 or 3 good threads will do so the grease fitting will be tight. Install the grease fitting but do not screw it all the way in. Just make it snug. Why is it not there from the factory? This is the only high wear area in the complete front and rear suspension of a Rincon. At 9 shots I felt slight resistance and at 12 shots the life giving grease was showing. Now it will be greased before every ride. The rest of the suspension will be tore down and greased every 2 or 3 seasons.
if you strip out your threads there are drive-in grease fittings available, but do not cause this problem. Practice on scrap.