not something you can repair yourself, ask the registered engineer that comes to repair and service it, if you can find one, most wont have a clue what that is
Why don’t you get the engineer that service’s it to take a look at it before buying parts you probably won’t need.
If as I suspect you haven’t had it serviced if you post your location there may be an engineer on this site in your area.
For those of us of a certain age, will know what the fault is before looking at it.
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