Thanks, Russ! I will have to remember to break in my new one. My old one, I guess, was broken in from lapping my stones over the past few months. And it did a fine job (as I reported earlier in this thread) up until last weekend.

After cleaning it with some Comet, I can actually see a discoloured spot on the DMT. My guess is when I was trying to get rid of the frown on the W&B I was working on, I started bringing up pieces of diamond, so now I have an uneven spot in the DMT. Live and learn. Keep my angles low on the DMT and get rid of the metal slurry often.