Badger trouble

Thanks to all! I will try replacing the washer and see if that helps.

The model 150 has a head very similar to the 200 (in fact I think most of the part numbers are the same). A parts breakdown is here: http://www.badgerairbrush.com/150parts.htm

Part no. 50-055 is a Teflon washer that fits between the head and body. Over time that washer will flatten and will cause the pulsation that you are seeing. The instructions for the model 200 say (in a little side paragraph) to loosen the head when the airbrush is stored to extend the life of that washer.

I have a 200 I still use occasionally, and every time it starts that pulsating I replace that washer and it will go away.

Make sure the nozzle is clean as it can have some dried paint in it. You can use a toothpick to fit into the nozzle to try and clean it out. Check to make sure the head is sealing and that the teflon washer doesn't need to be replaced.
John