motor alignment

I have read several posts on motor alignment and I'm sure mine is off. My shaft came loose out of coupling 2 years ago and I Manipulated it back into place without removing the hub from trans (V-drive). My question is how or where do you place the feeler gauge to check for adequate squareness or clearance? Reading these posts is bitter sweet. I'm thrilled to have educated advice, however, I'm finding more and more I need to do to my boat. I say that like it's a bad thing

You can find what you are looking for in the reference section of this site.

You may want to ask yourself why the shaft came loose from the coupling in the first place. Did anyone pull this shaft before and not tighten the set screws properly on the re-install. Something else that may be the cause is a bent shaft. This will cause vibration and could certainly result in a shaft coming loose. You might want to pull the shaft and take it to a prop shop and have it checked for straightness. Especially if you've every hit anything with the prop hard enough to cause prop damage. The shaft will almost always bend too. It's worth checking out!