I recently fixed a leaking TOTO WT152M In-wall toilet unit by replacing a part of the fill-valve assembly. Part of the THU134 fill valve assembly was leaking. I replaced the leaking plastic part with a new THU134 that I bought from Amazon. Finally, I also show you the Gerberit Seal Kit that a lot of people seem to be buying to replace the gasket in the THU134. Hope this helps!