Hi Joe,

We also have a delta plus, and we fire brand (torch) the ceramics, as recommended by many others (Frank Trensch told us about this approach).  Take a thin ceramic rod (we use an old thermal couple housing) and place one or two ceramics on at time and use a gas torch to get them red hot, and this should oxidize anything on the ceramics.   I would never use acid, as it takes a long time to "dry-it-out" the treated parts.  And I for one, am against putting/treating anything in the source with any acid. 

But, I would only do this with the ceramic holders and spacers , and if you have issues with the leads, then better use some emory paper or a use a dremel very lightly (when you write leads do you mean the feed throughs?).

All the best,

Bill Anderson
Earth Sci./SERC
FIU
Miami