Just a thought, maybe take a piece rubber hose that is a bit bigger than the sprayer nozzle. remove the hose off of the pump. Take your blow gun and back blow the whole system. I would feed the air in very slowly and lightly so that you don't blow a hose off of a connector inside somewhere. At your own risk…..

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Dave S.
Northeast
2003 4.6is
2005 E53 4.4
2003 E39 Msport(a REAL ONE!)
1959 Fiat 600