A tip from John, The Hoosier Huricane, on the Y-Block site.

"Let me guess. You were playing with the starter before you installed it and got the drive gear into the "crank" position, and now it only ratchets one way and won't retract. That restricts the room you have to work with. When I run into that, I hold the starter teeth against my spinning wire brush on the bench grinder so that it ratchets. If the brush is large enough and fast enough, the starter drive will retract and help tremendously when you install the starter."