DVD set ratings password bypass

If one purchases a used DVD player from the second owner and there is no way to reach the first owner and one wishes to set the "ratings" back to #8, not knowing the first owner's password, how does one reset the player back to factory defaults or whatever? The manual does not even address this issue not does the manual advise how to reset back to factory defaults.

Is there any widely-used trick, such as pushing and holding PLAY and STOP simultaneously or whatever?

The transport mechanism in question is a Matsushita/Panasonic DVD-A11OU/CA.

Thank you!