I recently bought a hill e 3000 compressor. No matter what pressure I fill to 3000 psi to 4350 psi it is always 400 psi short. I can set for higher pressure to take care of it but will only fill to 3900 psi on a 4350 fill. I tried the offset adjustment with no luck but am unsure if I set it wright. Any advice appreciated. This is my first post.glad to be here..