You are going to need a good 10X loupe...the $35 Belomo have very good lenses and coating....you can get a cheap 40X Chinese one....= to a real 10X, but not as good a lens. Costs @ $5 + or -. Good for a start.
Over time you are either going to get pens with nibs that are misaligned by the robot punters in the Postal System, or even you can casually bang your nib out of alignment.
You need a loupe....no magnifying glass will do....not even the 1 1/4th inch thick ones.
You have to see which nib is up, and either from the end of the slit or the breather hole, press your thumb nail down, so the top nib is under the low nib. Do that for 2 seconds twice and check....often needs three tries, seldom four.
German vintage '50-70 semi-flex stubs and those in oblique give the real thing in On Demand line variation. Modern Oblique is a waste of money for a shadow of line variation. Being too lazy to Hunt for affordable vintage oblique pens, lets you 'hunt' for line variation instead of having it.
www.nibs.com/blog/nibster-writes/nibs-germany & https://www.peter-bo...cts/nib-systems,
The cheapest lessons are from those who learned expensive lessons. Ignorance is best for learning expensive lessons.