I received the mouse with an Amiga 500, the seller mentioned yellowed parts and a partly-broken mouse. Well, it looked like I'm going to have some fun with using H2O2 again and practice with soldering some electronics. You can guess, I don't have photos about the original condition of the mouse...
Anyway, I connected the A500 to the tv and *boom* the magic boot screen appeared immediately and the Amiga loaded Workbench from a floppy disk in a minute. That was quite painless so far.
I had a testrun with the mouse to check its condition, well, the buttons were unstable and their clicking sounded broken. As an additional defect the left mouse button didn't work.
I was thinking, would an old but still working PC mouse be a good replacement? Let's ask the internet.
This was the best answer to my question, thanks to a user called Aidan on a random forum:
"Basically the problem is that a PC mouse has all the smarts inside. An Amiga mouse has all the smarts in the Amiga, and the mouse is dumb. You can either build the interface listed, or try and extract the quadrature signals from the mouse and push them down to the amiga."
Okay, then I need new knobs, and after a quick search I found them at AmigaKit.
C64 C motherboard, Amiga mouse board, 2 C64 power switch and 2 mouse replacement buttons
This one shows the replaced buttons together with the old stuff:
Clean mouse case, right after 3 days of H2O2 and UV light treatment:
I had to cheat a bit with the case because the new buttons are higher and stiffer than the originals and the mouse case became too tight. Used a small plastic piece, cut from the external part of a cable, glued them to the bottom part. Looks like somebody is mad, right? :)
This was just enough to lift the upper part a bit and the buttons can *click*.
There is a small crack on the left button but overall the mouse is nice, clean, white and everything functions as it should. This is the last photo, taken right after reassembly:
Today's music: Amiga demoscene compilation