I ran into a snag do this job...I have a decent valve spring compressor but when I compress the spring, the valve moves with it, it doesn't stick up to expose the keepers. I am using about 80lbs of compressed air to hold the valve in place but it seems almost stuck, when I've done this before there was no problem with the valve staying up. Is there a trick to this? Thanks for any input, I need the truck back!

 

Seems like the keepers (locks) were stuck. After compressing the spring I tapped on the compressor with a hammer and they came loose.