[Arran]

 You would not want to work on a 1950s era printed circuit board, especially one from around 1953, you look at one crosseyed and the foil will want to come off. Lets just say there was a reason why Brand Z preferred the hand wired chassis concept right into the 1970s in their TV sets, they had a go at it in the early 1950s, and had so many warranty claims that they decided to drop the idea and were skittish about it for a long time after that. Other then the "bumble bees" that set would be a decent candidate for capacitor re-stuffing, it does not look like any repair work was done under the chassis.
  With regard to the grille cloth I have had some luck using gojo for cleaning those, whilst still mounted to the board, then rinsed under the tap with hot water, and patted dry. I have also heard that brake cleaner may work on those too, but have not tried it, it did work on a flocked dial backing plate I had to clean up though, sprayed it on, then dabbed it with a paper towel, then repeated. If the brake cleaner was going to discolour anything it would have shown in my case, the flocking was black. 
Also, on the chassis bolts, it's unfortunate that they are all missing, maybe someone could take one out and check it with a thread gauge, maybe they were #12s with 32 TPI or 12/32, I doubt whether Philco would have used metric or BSW threads.
Regards
Arran