Please make extensive notes & some digital pictures will help during reassembly. If equipped with an oil pump it is usually behind the clutch (clutch is a left handed thread). Carefully check the hoses for cracks especially at bends and connections. Work your way through the linkage (use IPL to identify components and locations) cleaning and replacing any defective parts as you go.Start the saw and see if it oils when revved up (oozes down side of saw). Pay attention to the screen or filter on the free end (clean or replace, difficult to determine serviceability). Insert a blunted, hooked piece of wire through the oil filler hole and pull the hose in the oil tank out. Remove the clutch cover, bar, and chain, clean the bar groove, any holes and passages on the rear of the bar (both sides, consider rotating the bar), if equipped with a sprocket nose ensure it rotates easily at least one complete revolution.I know you have done most of this already But does it ooze with the bar off? I looked at the print and it appears there is a worm gear (item 50) and a driven pump (item 61) behind the clutch.

SOURCE: McCulloch EB428 chainsaw and the auto oiler won't work

Mcculloch mac 3200 parts diagram