Call Toto...I don't think it can be repaired.
One of my soft close seats has stopped functioning correctly after maybe... 2 years of use. It sounds like something within the hinge broke and it drops almost as fast as if it were a regular hinge. Are these repairable or do they need to be replaced? I tried searching online and only found other seat failures with no resolution. 2 years is way too short a lifespan IMO.
Call Toto...I don't think it can be repaired.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
No they can't be repaired.
Where are you located?
I decided to take the plunge and take the seat apart to see if it could be repaired and guess what. They can be repaired, and rather easily. At least in my case, once it was all apart I discovered the liquid in the hinge must have leaked out which was causing the failure.
I took photos with my phone along the way, but they didn't come out too good.
Basically there are two hinges, one on each side. One hinge controls the top cover and the other controls the seat. To get to the hinge you need to pull the hinge pin out of the over and seat. There are two plastic prongs that hold the pin in, but they can be bent open so the pin slides through. Once that's done there's another plastic prong that holds the hinge in the middle bracket. Once the hinge is free it can be pulled apart by removing 4 screws. The inner screws have tiny o-rings on them so make sure not to lose them!
Once the hinge was separated I noticed it had a viscous fluid that's basically squished between two sides of a channel. This provides the slowing mechanism. But mine was leaking and most of the fluid was gone. I refilled the hinge with some automotive grease figuring it was as close in viscosity as I had in the garage, put it all back together, and now I have a working hinge again!
As the owner of 5 Toto soft close seats, I'd really appreciate it if someone could identify the factory fluid , and a source for it if it's not a generic item like mineral oil.
I’m sorry but I cannot suggest any type of fluids to use or ways to repair. We do not have any specs on what is used in the hinge, nor do we have ways of fixing. Your best bet is to do exactly what you’re doing by researching on the web. We do not manufacture the seats themselves.
So, I will do the same as gerlando and substitute a material that approximates the same viscosity (and that I have available).
I used Gerlando's excellent instructions to open up the hinge on my seat. I don't think it's mineral oil. It is clear, sticky, and thicker than mineral oil. It reminded me of Kayro corn syrup, but thicker still. I used grease to replace the liquid, but it did not work for me. Will try again.
I suspect the fluid is glycerine.
So, is glycerine all that much more viscous than mineral oil?
Yes, glycerine is very thick, and sticky. It is not a lubricant at all.
I agree that the soft close mechanisms are probably filled with glycerine (clear, odorless, colorless, and sticky).
On my Toto, only the lid soft close had failed. The seat soft close was still working; it just could not handle the extra weight of the lid.
I didn't have any glycerine so, as a temporary 'fix', I swapped the lid and seat soft close mechanisms. The lid is used much more, so having the soft close on that is at least better than neither working.
I'm having the same issue with my 2 year old seat. ToTo replied that it must be replaced and cannot be repaired. I'm off to try and find glycerin to refill the hinges. The substance looks like silicone caulk when you squeeze it out of the tube.
I got a bottle of 100% veg. glycerine and filled both hinges. It is not as thick as the original material. It didn't fix my seat. I am going to give it more thought but think that grease might be a better choice. Vaseline could be a good choice also.
I filled the hinges with vaseline and still is a regular slamming down in the night toilet seat now. This seat is barely 2 years old. IMHO the functionality should be longer than 2 years. We are a low use location also, is just my wife and myself. This seat probably wouldn't last a year with a household with more than 2 members using it. It is also pitiful that Toto doesn't offer the hinges which can be easily replaced. Sorry Toto but I hope your toilet doesn't disappoint like the seat did. I replaced both toilets in my home with them.
I absolutely do NOT recommend purchasing this toilet seat.
While I think the Toto toilet is a superior design, I too am quite disappointed with their lackluster customer support stance on the soft close toilet seat. We are in a similar situation where it is just my wife and I and we never forced the seat closed. It is just too short a time with a modicum of use that has led up to the failure. I just can't believe that no one in Toto knows what viscous fluid was originally used in the soft closure mechanism. I still hope to make something work, but I will NOT be buying a replacement that Toto will continue to not stand behind.