seized air screws on carb

The adjustment screws for the idle mixture adjustment on my carbs are completely seized- one has the slots chewed up and the other one is not going to move. Anybody got any suggestions on how to unseize them? I've tried freezer spray to see if thermal shock works I would try drilling them out but I don't know the length of the threaded section and dont want to drill far enough in to damage the pilot air passage

SV carb screws are notorious - I'm planning to mess with my carbs soon and not looking forward to this bit!

Have you tried putting the screwdriver in place on the screw and gently hitting the end of the s/d handle with a mallet?

With the chewed up one you may need to dremel a slot in the head to put a flathead screwdriver in.

Once they're out replace them with stainless allen bolts - I THINK they're M5 x 10mm but I'll have to look into that to confirm...

HTH

Oop no that bolt size is for the choke plungers and float bowl screws, sorry...