5th airborne pin box setup - Raptor 3612ds

I installed the 5th airborne kingpin on our Cyclone 5 years ago. Recently I have been having trouble getting air into the bag. It worked great when new. Now, with the weight of the trailer on the hitch I can not get any air into the bag. I can get some air in with the weight off the pin but cant get up to the fill line. I have removed the valve stem and added air then allow it to escape. It seems to inflate/deflate as it should with no weight applied. I talked to Customer Service and they referred me to the Tech guys which I have yet to talk to.

Had not thought of going on line for their owners manual. Headed there now.

BTW, I love the kingpin when it is working properly.