Yamada Firmware Modification?

Hi everyone!

I am the owner of a Yamada DVR9300HX DVD/HDD-Recorder and I am trying to find a way to modify, disassemble or decompile its formware in order to alter and switch off certain functions.
As I don’t know what original recorder mine is cloned from, I mostly run into dead ends in my quest for information. I know that my recorder was sold in several european countries using brand names such as “Yakumo HDD Master” and “Oasis Media DVR9407”. The firmware file that I’ve flashed goes by the name “DVR9407_DE-D821P-692601_NG.UPD”. The capital P indicates that I’ve got a Philips tuner and “DE” makes it the German version (2.7).
I’ve already tried both ILOHack 1.5 and MTKReMaker but neither is able to read the firmware file. My next step would be to open the recorder to identify its components - unless there is another way to examine the firmware!
Now, what I am trying to do is to save my old VHS tapes from further deterioration. While most recordings cause no problems, some particularly poor sequences trigger the macrovision copy prevention mechanism. Following Murphy’s Law, these are the ones that i cannot skip… Now before anyone goes on to explain what AGC does and tells me to get a video stabilizer or a TBC - I don’t want that bypass. My interest lies in how to change my firmware to suit my needs!
It can’t be THAT difficult, now can it?

Kind regards and thanks in advance for any suggestions on the topic! Apologies if I’m rambling about things explained somewhere else ages ago!