If the drain cleaner or using a plunger does not clear the blockage, the U-bend assembly can be removed and cleaned quite easily.
Put a large bowl underneath the U-bend to catch the flow when the U-bend is removed.
On both corners of the U-bend, ensure to attach masking covering around the nuts. Try to use la pair of huge multigrips to loosen if the U-bend proves tough.
Pour extra water into a container after getting rid of the U-bend.
A coathanger can be used to get rid of the blockage. Once this achieved, you can go ahead to scrape gunk from your U-bend. Ensure to properly clean with a bottlebrush and detergent.
On the screw threads, smear petroleum jelly prior to replacing. It will help to facilitate removal next time.