There are tension specifications. For a full 5 inch reel with a radius of 2.3 inches on the supply side, the resistance should be 0.026 lbs. On the right
takeup reel it is 0.05 lbs.
Philips (did) mention that the method of obtaining this is by degreasing the felt and friction disk with carbon tetrachloride.
Dont !
I wrote an article in PF Reporter magazine in August 1965 and listed
Carbon Tet as a degreaser. Even then, there was much flack sent my
way, over that chemical.
http://www.americanradiohistory.com/...er-1965-08.pdf