I have had my B7800 for over twenty years and it has been pretty dependable. At some point the evacuator valve came off and was lost. How important is it to replace? The dealer recommended putting tape over the hole and putting a fine slit in the tape as a substitute. They didn't seem to think that buying a new valve was a necessity. My conditions are not very dusty, and I've never seen what I thought was a "dirty" filter, replacing them based on hours rather than appearance. Question: should I buy the valve or make do with the substitute? Thank you!