cleaning OCTO skimmer pump AQ-2000S?


My Octo Classic 150 Int skimmer has been working flawlessly for years.... Now the pump is not delivering its expected output. I have twice cleaned the needle-type diffuser inside the pump..... it worked for a while and got weak again.
I suspect that the diffuser is heavily coated with debris? Vinegar bath?
Has anyone had this condition?
I love that protein skimmer..... It is excellent.
Cleaning or buying a new pump?