Quoted from OchoFosho:
The game right now is at 1.41 with the 1987 code. He wanted to upgrade to 1.51 with the new 1987 code, but 1.51 isn't available anymore on Stern's website. Sorry, I'm used to doing this sort of thing just with audio files (Cleland mod on a GotG game) so maybe things work differently with video?
to update the code you will need to do the SD-Card process. The image on first page in this thread is the 1.51 code (please read 1. post). You download this code and unzip it.
if you want to to be save you can get a new SD-Card for your machine instead of overwriting the existing one.
Next step would be to plug in a USB-Stick go to menu -> utilities and save your settings.
Remove usb stick.
Plug the new SD-Card into your pc/mac and write the image to it (balena etcher, win32diskimager, Pinball Browser)
change the SD-Card out in the pinball machine, boot up.
plug in the usb-stick ->menu ->utilities -> load, to recover your settings.
if you would update the machine with the code provided on the stern site, either 1.51 or 1.52 this would overwrite all custom modification.
As i know the 1.52 may be soon released, but there seems to an issue with combination of insider connected, were custom code is recognized. So the new images are held back until tests are through and they are save to use. Changes in 1.52 are only minimal on gameplay, i think only little thing was changed.
Most changes are to insider connected, that may not be used with new code, but we will have to see.