I've an older IR-12 that was leaking beans in front, so I moved the drum forward, now it has a 1/8" gap which is what Diedrich's web site's recommondation. But now it is leaking beans thru the back, sometimes a lot, other times very little, and it doesn't matter if it's the first batch or not. For example 3 days ago, the 3rd batch was Brazilian Monte Carmelo, and it leaked like crazy, but nothing much during the 1st batch (Guatemalan Antigua) and 2nd batch(Yemen, small beans). Today's 1st batch was Indian Mysore, larger beans, yet there were some leakage, 2nd batch was Kenya, and not much leak. One thing I noticed, the last tow batches of Brazil had the most leak, and I roast more Brazil per batch than other beans. Anyone has any idea or theory? Also, any idea how much Diedrich charge for a new drum?