We have a Bunn coffee maker that has a "two pot" water reservoir, so when you add water there is an instant brewing process because there already is hot water inside. This week I noticed that the flow was literally down to a drip, now it takes triple the time to brew a pot of coffee. How do I get it to flow better? all I see is the vinegar method, but I'm afraid, with the reservoir, that I'll never be able to get all the vinegar rinsed out. I've heard of the term "delime." is there any special procedure or product for this?