This has come up on another forum. Let's say you specialise in
repairing/servicing vintage hi-fi. A customer brings a system to you to
repair the record deck but you see that the high voltage
valve/capacitor components are in a dangerous state. The customer says
just service the deck.

Do you have any duty to decline the repair/service as you can't return
the system in a safe state? Or any liability if you do?

I appreciate this isn't the same as say a gas boiler.