Lister Domestic pump

Hello Everyone,
I got a Lister Domestic pump, the problem is; the brass drainage screws on the outlet side. they are badly siezed and about to shred. I sprayed plenty of anti sieze spray from both sides and tapped with hammer but still no joy. can anyone tell me the trick?? i tried the biggest screwdriver and it still slips, is there any other tool for that? if i ruin those screws can i buy new ones? if so what size and name they are called and where can i get? apart from that everything seems ok so any ideas and help appreciated.
thank you

either heating it or leaving coke on it, or even petrol can work

I think the thread is 1/8npt. if they are that bad leave them in, paint over them and don't worry about them. You can always put some anti freeze in in the winter.

If you do not intend using them again and have alternatives to replace them then a good pair of stilsons will work a treat. Not an ideal answer but will get them out.

I replaced mine with 1/8 brass taps - looks great, and you never have to worry again.

regards

Martin

thanx guys, i think first i will look out for a spare pair of them, then go ahead and try to undo
cheers