<VV> boost retard testing

[Markpowhatan at aol.com]

My 63 turbo has recently started pinging rather badly when in boost.   I 
only use premium gas, and have looked for vacume leaks (none found) and have  
switched brands of fuel too.  Still it pings in boost, but not when pulling  
hills under a load.  I tried "checking" the boost retard to see if it is  
working by blowing down the hose to it with my mouth, but that doesn't move  
it.  Does it require more pressure than that?  I can push the arm with  a 
screwdriver, but that takes a lot of pressure to move it.  Is a  small air 
compressor needed to test it?   Thanks!  Mark Francis  63 turbo