HP Laserjet 4100 stopped working

[oldprinter19]

Some issues about the Laserjet 4100 have arisen now:
(note: I have only this LJ4100 for years, and never had any contact to the same model now or before).

I found in my pile of printouts an old(er) print of the 'Configuration Page' of this printer.
it shows (amongst other data) the
formatter number sch01a07te4
printer serial number <mostofnumbereditedaway>66
page count 591838
pages since last maintenance 48737
(I have no date for this page, but it must have been made before the printer stopped working.
I did not do any repairs in the years I own the printer, apart from changing the toner cartridge
and adding paper sheets).

Two days ago (I replaced the formatter board myself about 2 weeks ago for a used one)
I made a new printout for the Configuration Page just now
Referring to the same data as above, now these show the following values:
formatter number sch01a097w1
printer serial number <mostofnumbereditedaway>75
page count 283394
pages since last maintenance 258235

The fact, 'formatter number' differs I believe is true, as the formatter was replaced by me.
I cannot see though why the 'printer serial number' differs.
How is this possible??
And I cannot see why the 'page count' and 'pages since last maintenance' differ, as these should be
tied to the printer itself.

My impression: these indications the 'Configuration Page' presents are quite useless...

Hope you will be able to inform me on this.

[east2100]

The formatter number sch01a097w1 printer serial number [Personal Information Removed] page count 283394 come with the new formatter you replaced and that's why they are different from what you saw before.

They are the numbers of another 4100 which the formatter fitted on before you got it. 

[oldprinter19]

Thank you for that information. Strange to change a printer-identification though...

To the changed number of printed pages:

do I have to keep a personal (written) administration to be informed at what point in time the printer needs maintenance?

I guess this way of changing the state-of-use of a printer will not have rejuvenating impact on the fuser, rollers a.s.o.

(as my car will not live longer when I change the tachometer/mileometer for some item with less recorded miles/km's).

In what way Is a printer serial number sensible information??

(I edited/changed it in my post, because the administrator changed yours but not mine..).

oldprinter19