A clear service history is more useful than “serviced”

Keep invoices, workshop notes, photographs and removed components where available.

For each intervention, record the date, problem, diagnosis, work performed and parts replaced. If relevant measurements or adjustments were made, retain those details as well.

A phrase such as “fully serviced” does not reveal whether two capacitors or half the circuit were replaced.

Detailed records allow a future technician or buyer to understand what remains original and why particular choices were made.