Yamaha DTXpress/DTXplorer/DTXtreme

I have a DTXpress IV Special. I bought it in late May and so far my 
splash cymbal quit in the middle of a session. Turned out to be a 
loose output connection. It was fixed locally (I suspect the cause was 
poor soldering) and I got it back 2 weeks later. Now I'm finding the 
low and mid toms to have a "rattle" when I hit them. (not through the 
headphones or speaker - a "physical" rattle).

I use 5B sticks, which are a little on the heavy side, and I do hit 
the pads quite hard. I asked the sales guy if stick selection was 
important, and he said "No". Maybe I should flip the pads over and see 
if the screws loosened up.

Do other players "out there" have issues with non-electronic rattles 
or other strange sounds?