Help on Look p12 heel piece etc.

Found these Look P12s at a ski swap on Intuitive 74s. I still don’t know where the boot center should be on these skis but it only took a 1 cm remount of the heel rail to make these fit my buddy’s boot. The real question now is the din setting of the heel. I don’t mind experimenting with my own stuff but could use a little help on this, never having owned Look bindings and not wanting to be responsible for fucking this up. Any numeric indicator on the heel spring shaft is gone or not working. By not working, I mean, I can see what appears to be a small window showing a number five (although can't imagine these would go down to a five?)…..I assumed that once I start turning the spring, this number would go up or down. If this is not the din indicator, then any other numeric line is gone, worn off or whatever. The spring screw works fine, there is still a white line on the black plastic slide, but just no way of me knowing the amount of pressure I’m putting on the spring in terms of din setting. I could just crank it down all the way assuming a "12" , and then back off till I "assume" a 10….but like I say this ain’t for me and I would be more comfortable with some input.
Also, anyone know what that "cutout/button" is for on the heel spring shaft is for?

And, if anyone knows how to find the boot center on the Intuitive 74, I’d feel better about the new heel mount. I’m assuming that sooner or later the toe piece has to move forward once the heel is getting pushed back too far.

Thanks

edit- that "push button" I'm talking about is on the back of the heel spring shaft.

Somebody, shop tech or tool nut HAS to know what that "cut out" "push like" button is for on the Look P12 heel piece spring shaft. Don't make me go in.....

This frkn mystery has been solved....never spent time looking at "Looks"...but just came back from local shop where I had my Mantras mounted, against my better judgement to have someone else touch my skis but tomorrow might be the day to try these out...so a six pack went to shop tonight for quick fix and some "new" Look p14s......now I see the problem with the older p12s from the ski swap.....the plastic shroud that covers the basic heel piece casting is gone from both bindings...meaning, the din indicator shroud is gone.That is what that "button is for...to hold the shroud on....and that small window I spoke of must be a casting number.

I am an ass...I stared at these things for quite some time dissecting the foolishness of the design seeing how snow and ice could get compacted in around the spring...and why would anyone design a binding like this...
Now I'm pissed off that the plastic is missing and some a-hole was looking for 175 bucks for the setup...glad I waited till the end of the swap.

Anybody have any fucked up p12 heel pieces that I can swap plastic with?

If not, then stay the fuck outta my own personal thread bitches cause i'm on a roll..