.. Code to the computer at the alleyway

It looks quite fresh. Maybe it was tossed out from the Knitty Kitty Club recently. There ought to be something about it inside. Search the club.

Look from the basement. There is an interesting, but broken, printing press.

And it spat out a manual for Taste-O-Tron! That is your key into the machine.

There are two three digit codes separated by a minus sign in the manual.

I said the codes are separated by a minus sign...

Subtract the three digit codes from each other.

895 - 254 = 641