Recently purchased mark 5 for spraying mud , its the new mark 5 pro contractor hd 3-1. I've never used one before, old school hock and trowel and boxes for coating before this. This unit does not have the digital readout but has a bluetooth app that gives the pressure and it gets to 3300 psi but when spraying mud drops to 2500 psi on app. Thought maybe mud to thick but even thin does the same and my graco rep says it should be able to pump it right out of box. Tried with pail of water and spraying full blast outside and once again pressure on readout drops to low 2000's, my question is this, not having any experience running this machine for paint or mud can anyone confirm that this is normal operation that when you hold trigger open the pressure drops to that extreme and then when release trigger the readout goes back to 3300psi? Forgot to mention i'm running 100ft 3/8 line.