Quoted from High_End_Pins:Thanks.
The thing about the rails is that they can vary one side could be an 1/8 off from the other or more.
When it comes to older games all the nail holes make it even more difficult to rely on the old holes.
When you fill all you are starting with a blank slate and can make sure everything is even and symmetrical.
I’ve gone back and forth about continuing to make holes on the underside of the rails I make but rarely get feedback that they are too far off to be usable. Please let me know what you think.