Last night I installed my new decals in my Pin and it was easy for the very first time. This was the 5th set I've installed, and by far the quickest, smoothest (no wrinkles) and easiest (I did it by myself) I have ever experienced. I used the "wet method" for the first time using techniques from this old Pinball Supernova tutorial video. Essentially what you do is:
1. Open pin and lift playfield.
2. Take a bottle of soapy water (I did about 5 drops of dish soap in a 1 liter spray bottle) and wipe down inner sides of machine until slightly wet (and clean).
3. Remove 1 side decal and way flat on floor adhesive side up.
4. Spray soapy water over adhesive side of decal, it should be dripping wet when you pick it up.
5. Slide entire blade into place all at once, with lifted table sticking straight up (make sure lifted playfield. is pushed as far to the side away from your installation as possible, in my TSPP there was about a 1/4 inch of room between the side and the playfield).
6. Trim excess in back with an XACTO knife.
7. Firmly apply/stick down blade with moist paper towel, pushing out any excess liquid and removing any bubbles/wrinkles you may have.
8. Repeat steps 3-7.
9. Slowly lower playfield ensuring you don't scratch your newly installed blades.
10 Repeat step 7
This should work with any quality vinyl backed decal. I did this with the Tilt version but Pingraffix should work identically as well as any other side blade decal that is printed on vinyl. I tried it on the no-name brand Moes tavern sticker in the back right of this picture which does not seem to be printed on Vinyl, and could feel the material on the sticker starting to degrade so would not recommend this method on older stickers. When doing it this way you can sort of slide the entire sticker around for a minute or two before you hold it in place so adjusting it to exactly where you want is much easier.
In the end this took much less time than it usually does while resulting in a flawless installation with no wrinkles or bubbles.
I'm a big fan of sideblades and will be using this method going forward.