Hi Guys,
Thanks for your advice. I went and got the battery fully charged, and in the process found the wire going from the coil to the solenoid was melted and brittle. I thought this was the likely source of the problem and replaced both wires going to the solenoid. But when I put the battery back in and tried again, I had the same problem.
I removed the flywheel cover and noticed that the teeth on the starter were only just meshing with the flywheel teeth. The teeth had to move into the flywheel by about 1/4", shimming the starter only brings the starter down from the flywhel, which increases the distance.
I'm thinking I may have had the wrong starter on there the whole time. I went to a couple of local parts stores and they think it is the correct starter but weren't fully sure. The starter right now has offset bolts, but there are 3 bolt holes in the block, so I assume I could use a starter with offset bolts or lined up bolts.
If I tried a starter with the different bolt configuration, is there a chance that the gears would move over by1/4" and engage properly? I don't want to buy a starter and have it not work.
The numbers on the block are 3970010 and the transmission is a Turbo 400. Any ideas? It's driving me f***ing crazy. Thanks again