Here's the 44t spur gear:
http://www.rc-monster.com/proddetail...YOIF147&cat=40
And here's the 46t spur gear:
http://www.rc-monster.com/proddetail...YOIF148&cat=40
About the pinions - 5mm is 5mm so I have no idea why you're having trouble. I've never heard of anyone having this challenge. Sounds like the wrong size.