Hey Molesworth,
You are entitled to grow and learn in aiviation, as others of us have - to whatever degree (it can be difficult to determine on PPRuNe, particularly from just a few posts).
That said, it is your obligation to grow and learn.
The PPL is a "license to learn". There is just no way that a person can learn much beyond just being safe, during such a short training time. You'll have upwards of a thousand hours, and still find yourself learning. I have many times that, and learn new things regularly - even here! Though happily, the learning curve seems to be flattening out now!
You will find that as flying becomes "second nature" the actual readings of instruments at any moment will be less important to you (though you still must know and operate within limitations, whether properly marked or not). "Second nature" opens the door to complacency, but that's beyond the scope of this post.
As for
unless the fault is minor.
that's a Pandora's box for new pilots. New pilots probably cannot correctly judge "minor" vs. "major" correctly. An informal chat with the maintainer of the aircraft you fly, will bring you up to speed on what people are looking for. By the way, the absence of a correctly located, visible red line on a tach would definately be "major" and snag worthy.
For your reference, here's a guidline for the "major minor" determination in Canada. It can be carried across to un modified aircraft condition fairly well too, just read "suspected defect" in place of "modification"
Canadian Aviation Regulations - Part V, Standard 571, Appendix A
Pilot DAR