Stubborn Screws......

[bald eagle]

..... Bought the bj4 2nd hand... I need to change the chassis on it, as it has some serious collision damage from the previous owner..!!
I have come across some really stubborn chassis screws that doen seem to want to come out... So tighht in fact that they broke the tip off my hudy 1/16th allen driver.!!
What do people find is the best way to remove these screws? I dont know if they have been threadlocked in there, or are just really really tight. The onew I am struggling with are mostly connected to blue alloy parts.... cheers in advance guys...