Not impressed with them at all . Parents one is naff and has been replaced twice. They don't use toilet paper in it or allows Number 2's !
mine been in a few years and been fine but now the noise sounds different as it compressses the peanuts from your snickers
Probably best to fit a new one.
Or go onto saniflos web sight and it will have a list on engineers in your area that will work on them.
But be ready to pay £££££!
Ps I have fitted loads and fix a few but charge sh*t loads to fix them ( excuse the pun;)