In addition to what you have done, I also:
- flush the oil tank out with petrol/gas. Use a torch to find oil tank vent and exit line. Clean the filler cap and the surrounding area for good measure.
- then when everything is apart, you should see two holes on the oil pump -entry and exit. spray carb cleaner or WD40 in these holes plus the holes where they align on the case. You should be able to verify they are clear because carb cleaner will come out of the hole next to the bar and into the oil reservoir.
- if this still doesn't work clean everything really well and try thinning bar oil 50% and running it. Oil should spray everywhere. If it doesn't remove the clutch and open up the oil pump again to see if there is thin oil in there, then you can eliminate tank side issues and its probably an issue with the pump or worm gear.
- You might be able to disassemble the oil pumps to clean it but Im afraid I have not have to disassemble Husky ones before. Ive had success cleaning out Stihl oil pump mechanisms.