Hi and thank you for using Just Answer .
What has likely happened is that you have an obstruction with-in your unit that is preventing water to pass through the high pressure system. Since it has been in "storage" for sometime, I would have to guess that this machine wasn't properly stored and the water inside more than likely corroded some internal part(s). Now that you decided to use it again, the "fresh" water passing through the machine has picked up this corrosion and redeposited elsewhere where water has a restricted flow. It could be in the tip of the wand since you mention that you have water coming out without the hose attached. Anyways it would be the first place I would look. If you have any other questions, please ask. I wish you the best