Make sure your dampers and cap tops are in working condition. Aftermarket cap top quality varies. Some work, some don't. If you haven't replaced it for a year, replace them. They are not expensive to replace.
Fill up cap top couple times, locate the end of the cap top to the waste bottle, make a nut. fill up cap top again and now cleaning solution should stay on top of it. Move the carriage to the top of it, close the cap top. Turn off the power. Let is sit for 3 hours. Turn back on, perform strong clean. I would use choke cleaning under service manual. Good luck.