Air Compressor for an Cummins ISX question

Trick will not build pressure and is very slow to build, once it is built if quickly looses air pressure.

 

If I take the compressor head off and clean it and it is fixed that would tell me to replace the head correct? It currently holds pressure at like 65-70 lbs and may increase to 80-85 lbs while in low range or gunning the motor while parked, when I get to high range and am doing 65 mph up hill with a load it will build to cut out about 135 lbs. when not under load or stress will only built to 100 lbs.

i am trying to get this fixed without putting it in the shop and paying an arm, leg to fix it and me loose money for being down, and it end up being a simple fix.

 

also is there any photos or instructions online so I have a guide when doing this so I have an idea what I am doing?

 

What does that mean?

 

When draining my tanks I have been draining all three the wet, prim, second am I suppose to drain all 3 tanks or just the prim and secondary?

 

I have been draining them daily. and get a ton of water from the wet tank and a little bit from the primary and secondary tanks.