If you search on wiki.how there is a technique that used diluted vinegar. You need to test a small area to validate that the ink will not be disturbed. If it is good than continue.

Just found this topic. Four words: Photoshop is your Friend.
If you find you can't completely clean it up, You can always scan it and fix it up digitally.
Here's some samples of some pages I've done:

Williams Space Pilot Cover.

Original Scan:
IMG_20200120_0001 (resized).jpg

After clean up:
Space Pilot Cover 2 (resized).jpg

Stern Galaxy.

Original scan:
Galaxy-12 (resized).jpg

After clean up:
Galaxy Manual 9 (resized).jpg

Bally 2518 73 power supply:

Original scan:
Bally 2518 73 original s (resized).jpg

After clean up:
2518 73 Power Supply s (resized).jpg

I'd like to know if anyone out there also does this with old manual pages.

... also, If you don't want to pay the price for Photoshop, Photoshop LE works well for a much smaller price. Not as many features but it works.

Or you can also use the GIMP. It's free online, but they do ask for donations to keep it going.

I'd like to see some of those mistakes. I know Stern Electronics used to have loads of errors in the video game manuals back in the day. They didn't even try to make a decent manual for many of the games they licensed from Konami. Seems like a lot of games had listings for the six DIP switches from Scramble on games that had up to sixteen switches and more settings. And games like "Pooyan" had settings for "Rockets" instead of lives.

Editing, yeah that's doable. I've done it on some sheets that have temporary notes or drawings that were penciled in on them before. (I left that one note on the rare Bally power supply just for the history of it).

I'm working on an old scan for the Bally 6801 System Interfacer board now. LOADS of penciled in notes and crossed out stuff on what is a an otherwise fairly clean scan. I'm making all the noted changes on the schematic and doing the light clean up it needs.
I'll post the old and new copy later when I'm done.

Bump to see if there's anyone else who's doing this.

I did it for Bon Voyage. After I learned the machine I went through the manual, redid it, and fixed the errors. There were several. I did them in red so it would be possible to track the updates.

http://www.xsvtoys.net/files/Bon%20Voyage%20Installation%20and%20General%20Game%20Operating%20Instructions%20_revised_.pdf

I also redrew the playfield diagram from the Bally parts manual and made it all vector. Then made new charts for rubbers, lamps etc. Also made a custom rules sheet as that did not exist. All those docs are on this web page:

http://www.xsvtoys.net/bon_voyage_pinball_documents.htm

I also scanned and cleaned up the schematic, including fixing a few errors it had.

Later, I did a complete vector redraw of an EM schematic, but that’s another whole topic (Monte Carlo).

Sometimes I receive a scan from someone.
I would clean the images and stitch any that were done in multiple parts.
Sometimes I restore faded lines by copying other lanes and paste them where missing.
I use mainly Paint.NET
It's not perfect, but easy to work with.
I have a large collection of manuals and schematics (also Gottlieb).
I even share them with anyone who asks me.
In return I ask what the requester may have in return to build my collection.

Peter
http://www.inkochnito.nl

I was just looking over the schematic for Monte Carlo. Very impressive! this is way more than I've been able to do.