After having a few of these apart, I am not sure about the grease lube of that part. It always collects a bunch of dust in there and makes sticky dust cakes, but they all have been in good shape. I say light grease and keep on blowing that area out with compressed air.
I eliminated the open bearings for the arbor and used shielded, too much of a PIA to get to the grease fittings and it makes a sticky dust mess. Still rated for 2x arbors max rpm. Motor got 2RS, had shielded one side and no way to lube them, looked to be original bearings??