I have an unusual use for my hose-end Ortho sprayer (old style yellow one, found new on eBay). I am a dog groomer and use it to shampoo the dogs, and I have used an Ortho this way for many years. I add about a quarter-cup of shampoo concentrate to the jar, fill with water, and set it to a medium concentration to spray. (Can't remember the exact number). My latest sprayer, purchased just a few months ago, has stopped dispensing the shampoo unless I turn it upside down ( so the shampoo concentrate just flows into the tube ). This is quite annoying and rather difficult when the unit is wet and slippery already! The tube is not clogged, I've not only rinsed it out repeatedly, I've changed it altogether. Any thoughts? These older Orthos are discontinued and I detest the newer red one, it just does not work well for this use. Thank you in advance for any help.