Vacuuming the machine is a great idea. A reconditioned machine should not only be vacuumed, but WASHED as well. Playfield subway ramps should always be washed as well. I've seen countless "reconditioned" games with filthy subway ramps. When I check games I've restored months previously, I EXPECT the playfield to need a clean. Otherwise, I know the game is not being played.
I would not worry too much about the game's playfield being dirty after a couple of months. One of the reason's black rubbers were introduced to DMDs was because of the white rubbers became dirty too quickly.
DMDs attract more dirt because there are more moving parts.
