Graham;

I guess there's no question if you used the site search feature...this is certainly a thread from the archive...

Refer to the pictures of the construction of the FBs (Ref: https://www.sw-em.com/gastight_II.htm ) one can see because of the two piece construction of each terminal, that there is literally "strictly incidental force of a couple of bent over tabs occurring as a byproduct of holding the two separate terminals onto the plastic base" ...once these tabs are loose, you might be able to demount the FB to gain access to the rear, and rebend them to secure the terminal into the base better. Thankfully, those tabs are not in the current carrying path...

I don't know about filling the back with epoxy, as there are holes which would allow the epoxy to run out and away. I use non-leveling RTV for filling the back on the ones I rework...it is not susceptible to running out of the bottom and away...

Don't forget also, that the FB with single fuse in the early 1800s, the fuse should be changed to 10A rated 3AG type. See: https://www.sw-em.com/tech_bulletin_4.htm

Cheers