I'm restoring one I picked up a month ago too.
Here's a link to the thread.
https://pinside.com/pinball/forum/topic/cleaning-up-an-old-williams-grand-prix#post-5043308

I'd probably want to reset and glue any insert that isn't flat to the playfield whether i was using a protector or not.

For the cupped inserts I'm going to touch up the black outlines then fill in with clearcoat. I've seen people use small mylar disks to fill them in too with good results.

I removed my lamp sleeves. I didn't know they were red at one point! Mine were all yellowed.

I'm planning on using the warm white retro LEDs on the playfield anyway so I don't plan on using any sleeve.

I can't wait to finish mine!

-Paul

Just made an update on my Grand Prix.

Today at the York show there were TWO Grand Prix to play!
(don't think I've ever seen two of them at the same place before)

https://pinside.com/pinball/forum/topic/cleaning-up-an-old-williams-grand-prix#post-5250230

-Paul

IMG_20191009_172909864 (resized).jpg

Congrats! It looks great!

Been a while since I've updated my thread on the resto of ours, but here's the latest pic of where I am so far.

IMG_20200112_182334188_HDR (resized).jpg

I'm looking to make a new backglass for it with a little tweaking of the colors to match the colors we used on the cabinet.
Our's is just shot!

IMG_20190424_214340471 (resized).jpg

I love Atari_Daze's method to make a translite, and am trying to learn how to proceed.

-Paul

79 (resized).jpg

Right in front of the transformer on the RH side.

24 (resized).jpg

Hope this helps

-Paul

I've never seen any so I just repainted mine.

392 (resized).jpg

-Paul

http://www.pinballrebel.com/pinball/cards/

Scroll down to "Score Reel Numbers"

-Paul