Primary air tank won't build air

[jesse20]

The air on my 2011 prostar with a 2009 cm871 builds up air slowly SOMETIMES, this just started on tuesday no audible air leaks, bendix governor and air dryer were replaced, and same thing is still happening, the 1st tank looses air slowly while idling with and without load the air lines were checked from the compressor to the governor and they are not clogged up I did a DPF tune up but I only cleaned the components and only replaced the exhaust back pressure sensor about 7,000 miles ago. The secondary air tank holds its air between 100 to 120 psi at idle, when the primary tank detects around 65 psi it will build up SOMETIMES, and other times I have to rev up the engine to get it to build at 120 psi, and sometimes it just won't build past 85 psi on both tanks. PLEASE HELP thanks. The pictures shows how my compressor looked when i did my EGR tune up.