Looking a photo #1, it doesn't look like a zerk fitting. It looks like a bolt holding the trunnion pivot to the weight bar.
Because on my Equalizer brand WDH they say to lubricate the hitch head pivot sockets, IMO your trunnion pivots should be lubricated.
Of course free advice is worth every cent you paid for it.
Sherm & Terry w/rescue Eydie (min Schnauzer) & Charley (std Poodle)
2015 Jay Flight 27RLS, GY Endurance (E), Days: 102 '15, 90 '16, 80 '17, 161 '18
2006 Ford F350 PSD, 4WD, CC, LB, SRW, Cmpr. pkg, Equal-i-zer 4-p, Continental ContiTrac TR