buffer overflow, discover bad chars

I have successfully completed the buffer overflow series.
I was looking for older programs and came across mswlogo(url:https://mswlogo.en.softonic.com/) where it crashes at 250 chars.
I wanted to ask if it would be possible to create an exploit from it.
I tried it but when I search for the bad chars with mona.py (Immunity debugger).it comes out something different every time.(for example:
If I try all chars \x00\x01 comes out as bad char.
If I omit \x00\x01 it comes up with \x00\x01\x02 as bad char.
If I omit \x00\x01\x02 \x00\x01\x02 comes out as bad char and so on).
I would ask if you could test it and how you did it, or if it doesn’t work for some reason.