Vagrant
GT Reference
finally got off my ass and looked at it closely. you should be able to blow up from the gearbox through the vent to relieve pressure but not suck in. mine passed air both ways. i pried off the top cover there is a plastic insert in there and there should be a steel? ball in there that sits on the hole into the rear end. mine had no ball in there. plastic sleeve is .200 thousands and the only small ball i had laying around was a plain old BB. measures about .173. close enough! I dropped it in put the cover back on and covered 2/3 of the open area with RTV silicone. hopefully problem is solved.