My backyard neighbor finally got a leaky pipe fixed. Turned out to be a pipe that wasn’t glued when the pool went in many years ago and was constantly seeping. It took a few different pool companies to find it.
Good luck!
It doesn’t hurt to ask if you can bring your mechanic out to look while it’s opened up. I would be worried if they said no.
Depending where you are located, you can ask around for mechanic names and see who is available to help.