I've read
somewhere the mechanical puncher unit is not made by DEC but
by some other company.
Is there any known documentation about the DEC PC05 puncher ?
There are several manuals at bitsavers. Why didn't you even bother
checking before posting?
http://bitsavers.trailing-edge.com/pdf/dec/papertape/
And which of those manuals covers the punch mechanism? Did you bother to read
any of them before flaming?
The OP is right, the punch mechanism is not DEC. I believe it was Roytron. There are
some Roytron manuals on bitsavers, the punch shown there looks like the
mechanism in my PC04/05 but I can't be sure, there may be subtle differences. But
those might be worth a look.
-tony