NotSpaghetti
We have a great soft-close lid on our downstairs toilet. It's been there for maybe 20 years... the upstairs one is not soft-close and between that and the high-level WC "thunderbox" it's a wonder anyone can get a lie-in.
Sorry this is a bit of a red herring but I often forget which is which!
I hope someone can help you repair your soft-closer!
We had new ones fitted last year, soft close and they can be removed at the push of two buttons for thorough cleaning.
The plumbers who sold them fitted one, DH fitted the other but I'm not sure of the make, sorry.