I believe those motors with the hole in the housing are also supposed to have a rubber vent tube with a grommet-style groove installed in the hole. The ones I've seen with the vent wrap around the motor housing so the bottom of the vent tune points down.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!