HOW TO DIAGNOSE A STARTER PROBLEM with your vehicle

My VW TDI Jetta wouldn't start when I came out of the grocery the other day, but I was able to push it & clutch start it on my own in order to get home.
Charged the battery overnight, hooked it up next day, & same issue.
Is it the starter itself, or something else?
Starters are very expensive nowadays, so if we don't have to replace it, we won't. Here's how you figure it it's the starter, or something else.

[@chrisgreene9147]

Nice job brotha

[@Smittyschannel]

thank you broham 😁