Mike I purchased a 20 pound Harbor Freight pressure blaster this past summer to clean up some nasty rust posts, rust pitted surface areas and inaccessible nooks and crannies on my cab. I experienced some of the issues you had been confronted with. Dry blast media is very important , but my issue was poor media flow from the bottom of the pressure tank. The weird zinc plated combo fitting on the bottom, similar to the Eastwood models was the issue and a chronic clog point. I replumbed it with 1/2 NPT black pipe and flow has been consistent and strong. I used fine grit Tractor Supply Black diamond grit. Can be reused 3 times. Took the rust down to white metal easily even with pits at 85 psi. Not sure if this is your problem but something to ponder if your issues persists. Happy blasting. Wear a good mask!! Mike
