My professional mechanic buddy, who owns his own shop, has not, for years, been able to find a competent mechanics helper.
Bit problem!
Is he willing to train people?
What I would do instead of putting an ad in help wanted, I would put an ad asking for people willing to learn the trade.
Instead of the standard interview, I would give them an aptitude test.
Layout the basic tools and ask them to perform the task.
If they have natural aptitude it will be obvious.
What you look for next is their attitude and enthusiasm for the work.
I'm sure there are many people who have mechanical aptitude but they aren't being given an opportunity to prove themselves.
Trade schools are good but they likely attract 'people looking for a job' rather than people willing to prove their worth.
Kids today cannot even read analog clocks-—they want all the clocks in schools changed to digital!!!
How should anyone expect them to read a dial gauge or use a calipers???