I have a 2004 Yukon Denali XL with the hitch package on it. I pull my 26' Travel Trailer and lately have found that the hitch is sitting to low and the shocks aren't holding the air. I can hear the compressor come on but they don't lift quickly like they used to and then the compressor will click off and they will be to low and the hitch will often scrape/bottom out. My question is could this be a shock problem (shocks not holding air) or could it be a compressor problem? I do hear the compressor coming on and then clicking off like it always has. Thanks for any help!