Try using these things with your cleaner in it.. Insert into the pick up and squeeze and pull back on the lever of the gun into a bucket of H2O. Does a real nice job of cleaning out the previous color. Then a Q tip into the pick up tube to clean it out even better. Thank canalman for the q-tip tidbit and I think Bernzy told me about the wash bottle.
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http://www.usplastic.com/catalog/pro...uct%5Fid=14757
This company has anything you need when it comes to plastics. P.