sounds like 2 problems, are you getting alot of blue arc from the contact screw ? might be time to change the capacitor, it might be fuseing together a bit.. and keep it the screw/spring clean, windex works really well (someone tipped that off in another thread) as for the residual magnatism, you could run it over a degausser (de-magnatizer) go to walmart or a similar store and ask the cashier nicely if she would do it for you. I heard you can smack it with a piece of steel too, never tryed it tho, i havint had this problem much.
It sounds like your machine is due for a overhaul, if it were me i would probally just rebuild it, if you dont want to do that then i hope what i suggested helps you out. either way i would suggest taking it apart and cleaning your electrical contacts and changing the capacitor and springs and de-magnatize it.