As RedHorse1 suggested, check the bolts first. The AC unit sits on the gasket and the gasket compresses over time. Often snugging down the bolts will do the trick. Much easier to give that a try first.
Sherm & Terry w/rescues Steve (std Poodle) & Eydie (min Schnauzer)
2015 Jay Flight 27RLS (Camped: 102 nights 2015, 90 nights 2016)
2006 Ford F350 6.0 PSD, Lariat, 4WD, CC, LB, SRW, auto., Camper pkg.