Hmmm I see your dilemma --My similar vintage SFGH's have 4 strategically placed Phillps screws to enable the terminal holding plate to easily be removed/etc Your series 1 Amator ( And the BEST Sounding version!) have that one piece Block plate which seems to be fixed from the inside-- whereas the Series II's have the 4 screw Terminal Plate on the rear.
Unless you feel proficient to remove the Drivers I'd certainly advise an experienced trusted hand take on the chore--you stuff up those unobtainium Esotar Tweeters and its good night Nurse

.Remember to torque wrench the Drivers when replacing.
These times can be trying so tread carefully and good luck.
BruceD