Received an Echo 452vl the other day and can't get it running. It seems to have great compression, has spark, I cleaned and kitted the carburetor and checked the fuel lines and filter, they seemed okay. Pull the choke and it hits four or five times like normal, but when you push the choke in it may pop once and that's it. I've tried all different adjustments on the H and L screws but to no avail. Think a pressure/vac test is needed or not? I've put off doing that because it's a little different than the Stihls I normally work on and I'll have to rig up the equipment..