I have been cleaning all of my equipment with vinegar and this has always worked well. However recently i have had several brews that have been flat after the relevant brewing period and I have changed nothing about the process. I have always used the Coopers home brew kits and their canned brews without problems. All bottles are completely sealed with no leaks and all have been primed with Coopers carbonated drops as per their instructions. Could using the vinegar as a cleaner be the causing the problem with flat brews?