Hi patg23,
When it comes to these definitives stamps like AM or Bauten or others, it becomes a full life span collecting :).
Here an example by using the Nr.16 (German printing)
We will play only with the bottom of the sheet.
First you have to make the difference between real PLF and field charateristics.
Here is the bottom sheet of Nr.16

Now since members from the study group spent a lot of time gattering information here is the credit. Reference:
https://www.arge-am-post.de/Remember, there is a lot of work in there. So give credits when it is time to do so.
Now we will use an extract from the site that you can download (Thanks to them)
So at position 93 we see this, a big white spot on the right numeral 1.


By using this chart we can see at R 4-5 position 93 and type 3 sheet. What you see in red are Michel PLF so this one correspond to Michel PF I. Those in blue are PLF from the study group (Real PLF like those in Michel). All others in black are field characteristics (Feld Merkmale) and not real PLF. With these you can find the type of sheet. This is a simple one because we already know the type of sheet because PF I is only on Type 3.
So if you go in your Michel special 2 for German Printing, you will see Nr.16 PF I Type 3 sheet. Go down a little and find Nr.16 PF X position 60 notice Type 3 and 9 sheet. So why not going back to the bottom of sheet and look for position 60. Left numeral 1 broken.


So on the chart this flaw appears on D 2-3 position 60 and Type 3 and 9 sheet.
Again in red Michel PLF, blue Study Group PLF and in black field charateristics.
Now let see a field charateristic by using the last chart and on bottom of sheet (position 51-100) also applying to Type 3 sheet because we know it is Type 3.
First one is under D at position 68 in D 4. Notice the small grey dot in the left numeral 1. This is not a real PLF. But still a variety.


Interesting serie to look at and specialize. So for your question for the second stamp, if not in Michel, surely a Study Group PLF that you will find in their publications.
Best regards
Hornet