Midget brake adjustment

[Eric Bartels <bartels@maths.ox.ac.uk>]

Hi there, 
the other day i was trying to adjust the rear drum brakes on my 73 
midget. But the screws wouldn't turn for the life of me. 
I already applied copious amounts of wd40 from the outside but still 
could not move them. Any tips ? Should i apply more wd40 from the inside 
? What should I do if i gever get them loose ? Use copper grease ? Or are 
there replacement screws which do not rust in ?

Cheeers, Eric