Flipper hold isn't supposed to necessarily pull the flipper up - its job is to hold the flipper up once it's flipped with the power stroke with less power so the coil doesn't burn.

You have an exceptionally strong flipper hold winding on your left flipper if the hold pulls it up (even slowly). There's still nothing wrong with it, though, as long as the flippers flip and hold themselves up. You're looking for a non-existent problem.

Now, if the flippers don't flip (in test or gameplay) and STAY up as you hold the button, yes, there's an issue.