To diagnose or troubleshoot means to SEARCH for and IDENTIFY (or verify) the source of a problem.
Once the problem is identified, a repair can be performed, based on the part(s) availability/cost and the mechanic's availability/cost.
So the availability and cost of the PART(S) (if needed) and the LABOR, will determine whether you give permission for the REPAIR.
The repair cost may/will be added to the diagnostic labor cost.
How much is in your wallet?
Good luck!
p.s. In my state, the repair parts costs and the estimated labor costs must be provided to the customer in writing BEFORE any repairing can begin. Their signature (written permission) must be given for a repair to commence. This procedure prevents the customer from being surprised by a repair cost, and then not wanting to pay afterward.
FULL DISCLOSURE + PERMISSION combine to make a sensible legal contract for both parties.
-Engine overhaul mechanic and general automotive mechanic since 1972